Weakly ionic aqueous suspensions of ground mineral matter and their uses

ABSTRACT

The invention relates to the use of a weakly ionic and water-soluble copolymer as a grinding aid agent for grinding mineral matter in aqueous suspension in order to obtain aqueous suspensions of refined mineral matter, with a dry matter concentration that can be high, with a low Brookfield™ viscosity that remains stable over time, having the property that it presents a pigmentary surface area the ionic charge of which, as determined by ionic titration, is low. 
     The invention relates to the aqueous suspensions of mineral matter obtained and their use in the fields of paper, paint and plastics.

The present invention relates to the technical sector of suspensions ofmineral matter and their applications in the fields of paper, paint andplastics, and more particularly their applications in the paper industrywith a view to improving either the paper sheet manufacturing process,or the sheet treatment process, or the sheet properties.

The invention firstly concerns aqueous suspensions or “slurries” ofrefined mineral matter, with a dry matter concentration that can behigh, that are weakly ionic and have a low Brookfield™ viscosity thatremains stable over time, that is to say it relates to aqueoussuspensions of refined mineral matter, with a dry matter concentrationthat can be high, with a low Brookfield™ viscosity that remains stableover time and having a pigmentary surface area the ionic charge ofwhich, as determined by ionic titration, is low.

These aqueous suspensions are intended for pigmentary applications inthe field of paper, paint and plastics and are used more particularlyfor paper applications such as paper coating and/or surface treatment ofthe paper, or such as the filler during the manufacture of the paper,board, or analogous sheets.

This use as filler can be direct as composition of filler duringmanufacture of the paper, board, or analogous sheets, or indirect asrecycling composition of coating brokes when the recycling compositionsof coating brokes are used in the manufacture of the paper, board, oranalogous sheets.

The invention also relates to the use of a weakly ionic andwater-soluble copolymer as a grinding aid agent for grinding mineralmatter in aqueous suspension in order to obtain aqueous suspensions or“slurries” of said refined matter, with a dry matter concentration thatcan be high, with a low Brookfield™ viscosity that remains stable overtime, and having the property that it presents a pigmentary surface areathe ionic charge of which, as determined by ionic titration, is low.

The invention also relates to the use of same copolymer as dispersionagent of the filter cake obtained during an intermediate stage in themanufacture of refined mineral matter suspensions, with a dry matterconcentration that can be high, with low Brookfield™ viscosity thatremains stable over time and having a pigmentary surface area the ioniccharge of which, as determined by ionic titration, is low, thisintermediate stage taking place after grinding and before thermalreconcentration.

The invention also relates to said grinding aid agent by means of whichit is possible to obtain aqueous suspensions of said refined mineralmatter, with a dry matter concentration that can be high, with lowBrookfield™ viscosity that remains stable over time and having apigmentary surface area the ionic charge of which, as determined byionic titration, is low.

The present invention moreover relates to the grinding process thatimplements said grinding aid agent.

Moreover, the invention relates to the use of said aqueous suspensionsof mineral matter before or after drying or re-dispersion after dryingin the field of paper or paint, and after drying in the field ofplastics, and more particularly in the field of paper for paper industryapplications such as, in particular, paper coating and/or the surfacetreatment of paper, or such as the filler, whether the latter implementsa direct composition of filler or a recycling composition of coatingbrokes.

It also relates to the use of said aqueous suspensions of mineral matterin a drying process after grinding.

Finally, it relates to paper, board or analogous products manufacturedand/or coated according to the invention.

In the manufacturing process of a sheet of paper, board or analogousproduct, the skilled man in the art increasingly tends to replace partof the expensive cellulose fibres by cheaper mineral matter in order toreduce the cost of the paper while improving its properties.

This mineral matter, familiar to the skilled man in the art, comprises,for example, calcium carbonate and miscellaneous analogous fillers suchas dolomite, gypsum, calcium hydroxide, satin white, titanium dioxide ormixed carbonate based fillers of various metals such as, in particular,calcium associated with magnesium and analogues, various matter such astalc or analogues, and mixtures of these fillers, such as, for exampletalc-calcium carbonate or calcium carbonate-kaolin mixtures, or mixturesof natural calcium carbonate with aluminium hydroxide, mica or withsynthetic or natural fibres or co-structures of minerals such astalc-calcium carbonate or talc-titanium dioxide co-structures.

For a long time now it has been quite common to use, as grinding aidagents, water-soluble polymers based on polyacrylic acid or itsderivatives (FR 2 488 814, FR 2 603 042, EP 0 100 947, EP 0 100 948, EP0 129 329, EP 0 542 643, EP 0 542 644) to provide aqueous mineralsuspensions that meet the above-mentioned refinement and viscositycriteria, but these grinding aid agents are polymers and/or copolymersof the anionic type which have the disadvantage of requiring theaddition of cationic compounds during the paper sheet manufacturingprocess when the aqueous mineral suspensions containing them areimplemented in these sheet manufacturing operations.

The end user therefore strives to minimise the polymer agent demandduring paper manufacture, for every median diameter and/or for everypoint of the grain size curve of the particles of mineral matterimplemented.

To solve the problem, the skilled man in the art is currently familiarwith the solution recommended in patent application FR 2 810 261, whichhas the disadvantage of not fully meeting the end user's needs becausealthough this solution makes it possible to obtain aqueous suspensionsof mineral matter with low ionic charge, it does not make it possible tohave suspensions with a sufficiently low ionic charge to correspond tothe end user's needs.

Moreover, the paper manufacturer who is the end user is faced with theproblem of implementing coating colours which are not sufficientlystable during paper coating operations.

The skilled man in the art, being familiar with this problem, also seeksto develop aqueous suspensions of mineral matter which make it possibleto obtain coating colours which are highly stable even at low anionicityand for every median diameter and/or for every point of the grain sizecurve of the particles of mineral matter implemented.

Faced with the above-mentioned problems, the Applicant took thesurprising step of developing aqueous suspensions of refined mineralswith dry matter concentration that can be high, with low Brookfield™that remains stable over time, and having a pigmentary surface area theionic charge of which, determined by ionic titration, is very low,suspensions the implementation of which, both in the paper manufacturingprocesses and in the filler or in the paper sheet treatment processessuch as coating, make it possible to solve the above-mentioned problems.

These aqueous suspensions of refined minerals with dry matterconcentration that can be high, with low Brookfield™ that remains stableover time, and having a pigmentary surface area the ionic charge ofwhich, determined by ionic titration, is low, are obtained by using aweakly charged polymer as a grinding agent of the mineral matter inaqueous suspension, or by using the same copolymer as dispersing agentof the filter cake obtained in an intermediary stage of the manufactureof the suspension, this intermediary stage taking place after grindingand possibly before a physical concentration process such as thermalconcentration.

The said aqueous suspensions of refined mineral matter with dry matterconcentration that can be high, with low Brookfield™ that remains stableover time, and having a pigmentary surface area the ionic charge ofwhich, determined by ionic titration, is low, are characterized in thatthey contain, as a grinding aid agent, a copolymer consisting of:

-   -   a) at least one ethylenically unsaturated anionic monomer having        a monocarboxyl function selected from among the ethylenically        unsaturated monomers having a monocarboxyl function such as        acrylic or methacrylic acid or hemiesters of diacids such as C₁        to C₄ monoesters of maleic or itaconic acid, or mixtures        thereof, or having a dicarboxyl function selected from among the        ethylenically unsaturated monomers having a dicarboxyl function        such as crotonic, isocrotonic, cinnamic, itaconic, maleic acid,        or anhydrides of carboxyl acids, such as maleic anhydride or        having a sulfonic function selected from among the ethylenically        unsaturated monomers having a sulfonic function such as        acrylamido-methyl-propane-sulfonic acid, sodium        methallylsulfonate, vinylsulfonic acid and styrenesulfonic acid        or having a phosphoric function selected from among the        ethylenically unsaturated monomers having a phosphoric function        such as vinylphosphoric acid, ethylene glycol methacrylate        phosphate, propylene glycol methacrylate phosphate, ethylene        glycol acrylate phosphate, propylene glycol acrylate phosphate        and their ethoxylates or having a phosphonic function selected        from among the ethylenically unsaturated monomers having a        phosphonic function such as vinylphosphonic acid, or mixtures        thereof,    -   b) at least one non-ionic ethylenically unsaturated monomer of        formula (I):

where

-   -   m and p represent a number of alkylene oxide units less than or        equal to 150    -   n represents a number of ethylene oxide units less than or equal        to 150    -   q represents an integer equal to at least 1 and such that        5≦(m+n+p)q≦150, and preferably represents an integer such that        15≦(m+n+p)q≦120,    -   R₁ represents hydrogen or the methyl or ethyl radical    -   R₂ represents hydrogen or the methyl or ethyl radical    -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R′ represents hydrogen or a hydrocarbon radical having from 1 to        40 carbon atoms, and preferably represents a hydrocarbon radical        having from 1 to 12 carbon atoms and even more preferably a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   or a mixture of several monomers of formula (I),    -   c) at least one organofluorinated or organosilylated monomer,        preferably selected from among the molecules of formulae (IIa)        or (IIb) or (IIc) or mixtures thereof:        with formula (IIa)

where

-   -   m1, p1, m2 and p2 represent a number of alkylene oxide units        less than or equal to 150    -   n1 and n2 represent a number of ethylene oxide units less than        or equal to 150    -   q1 and q2 represent an integer equal to at least 1 and such that        0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150,    -   r represents a number such that 1≦r≦200    -   R₃ represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R₄, R₅, R₁₀ and R₁₁ represent hydrogen or the methyl or ethyl        radical    -   R₆, R₇, R₈ and R₉ represent straight or branched alkyl, aryl,        alkylaryl or arylalkyl groups having from 1 to 20 carbon atoms,        or a mixture thereof    -   R₁₂ represents a hydrocarbon radical having from 1 to 40 carbon        atoms    -   A and B are groups which may be present, in which case they        represent a hydrocarbon radical having from 1 to 4 carbon atoms        with formula (IIb)

R-A-Si(OB)₃

-   -   where        -   R represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   A is a group which may be present, in which case it            represents a hydrocarbon radical having from 1 to 4 carbon            atoms        -   B represents a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIc)

-   -   where:        -   m3, p3, m4 and p4 represent a number of alkylene oxide units            less than or equal to 150        -   n3 and n4 represent a number of ethylene oxide units less            than or equal to 150        -   q3 and q4 represent an integer equal to at least 1 and such            that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150,        -   r′ represents a number such that 1≦r′≦200,        -   R₁₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₁₄, R₁₅, R₂₀ and R₂₁ represent hydrogen or the methyl or            ethyl radical        -   R₁₆, R₁₇, R₁₈ and R₁₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   D and E are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,    -   d) possibly at least one monomer of the acrylamide or        methacrylamide type or their derivatives and mixtures thereof        such as N-[3-(dimethylamino)propyl]acrylamide or        N-[3-(dimethylamino) propyl]methacrylamide, and mixtures        thereof, or at least one non water-soluble monomer such as the        alkyl acrylates or methacrylates or mixtures thereof,        unsaturated esters such as        N-[2-(dimethylamino)ethyl]methacrylate, or        N-[2-(dimethylamino)ethyl]acrylate or mixtures thereof, vinyls        such as vinyl acetate, vinylpyrrolidone, styrene,        alphamethylstyrene and their derivatives or mixtures thereof, or        at least one cationic monomer or quaternary ammonium such as        [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [2-(acryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [3-(acrylamido) propyl]trimethyl ammonium chloride or        sulphate, dimethyl diallyl ammonium chloride or sulphate,        [3-(methacrylamido) propyl]trimethyl ammonium chloride or        sulphate, or mixtures thereof    -   e) possibly at least one crosslinking monomer selected, but not        exclusively, from the group consisting of ethylene glycol        dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate,        the allyl maleates, methylene-bis-acrylamide,        methylene-bis-methacrylamide, tetrallyloxyethane,        triallylcyanurates, allyl ethers prepared from polyols such as        pentaerythritol, sorbitol, sucrose or others        the total of the components a), b), c), d) and e) being equal to        100%        and having an intrinsic viscosity less than or equal to 100 ml/g        as determined in accordance with the method described in        Vollmert publication “Outlines of macromolecular chemistry”        volume III, Vollmert Verlag, Karlsruhe 1985 and by the        implementation of a solution of demineralised water and a        capillary tube defined in standard DIN 53101/0a, of constant        0.005 and diameter equal to 0.53 mm. This method will be        referred to as the intrinsic viscosity method in this        application.

A second method that can be used to determine the intrinsic viscosityuses a 6% solution of NaCl and the same equipment as described above.

In the examples where this second method is used in addition to thefirst method, the intrinsic viscosity values obtained using this secondmethod correspond to the second value indicated.

Thus, in order to minimise the cationic agent demand when manufacturingthe paper, for every median diameter and/or for every point of the grainsize curve of the particles of mineral matter implemented and in orderto provide, when coating the paper, coating colours which are highlystable for every median diameter and/or for every point of the grainsize curve of the particles of mineral matter implemented, the prime aimof the invention is to provide such aqueous suspensions of refinedmineral substances containing the above-mentioned copolymers.

Another aim of the invention is the use, as a grinding aid agent formineral substances in aqueous suspension or as dispersing agent of thefilter cake obtained in an intermediate stage of the manufacture of thesuspension, said intermediate stage taking place after grinding and, ifrelevant, before a thermal concentration process, of a copolymerconsisting of:

-   -   a) at least one ethylenically unsaturated anionic monomer having        a monocarboxyl function selected from among the ethylenically        unsaturated monomers having a monocarboxyl function such as        acrylic or methacrylic acid or hemiesters of diacids such as C₁        to C₄ monoesters of maleic or itaconic acid, or mixtures        thereof, or having a dicarboxyl function selected from among the        ethylenically unsaturated monomers having a dicarboxyl function        such as crotonic, isocrotonic, cinnamic, itaconic, maleic acid,        or anhydrides of carboxyl acids, such as maleic anhydride or        having a sulfonic function selected from among the ethylenically        unsaturated monomers having a sulfonic function such as        acrylamido-methyl-propane-sulfonic acid, sodium        methallylsulfonate, vinylsulfonic acid and styrenesulfonic acid        or having a phosphoric function selected from among the        ethylenically unsaturated monomers having a phosphoric function        such as vinylphosphoric acid, ethylene glycol methacrylate        phosphate, propylene glycol methacrylate phosphate, ethylene        glycol acrylate phosphate, propylene glycol acrylate phosphate        and their ethoxylates or having a phosphonic function selected        from among the ethylenically unsaturated monomers having a        phosphonic function such as vinylphosphonic acid, or mixtures        thereof,    -   b) at least one non-ionic ethylenically unsaturated monomer of        formula (I):

where

-   -   m and p represent a number of alkylene oxide units less than or        equal to 150    -   n represents a number of ethylene oxide units less than or equal        to 150    -   q represents an integer equal to at least 1 and such that        5≦(m+n+p)q≦150, and preferably represents an integer such that        15≦(m+n+p)q≦120,    -   R₁ represents hydrogen or the methyl or ethyl radical    -   R₂ represents hydrogen or the methyl or ethyl radical    -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R′ represents hydrogen or a hydrocarbon radical having from 1 to        40 carbon atoms, and preferably represents a hydrocarbon radical        having from 1 to 12 carbon atoms and even more preferably a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   or a mixture of several monomers of formula (I),    -   c) at least one organofluorinated or organosilylated monomer,        preferably selected from among the molecules of formulae (IIa)        or (IIb) or (IIc) or mixtures thereof:        with formula (IIa)

-   -   where        -   m1, p1, m2 and p2 represent a number of alkylene oxide units            less than or equal to 150        -   n1 and n2 represent a number of ethylene oxide units less            than or equal to 150        -   q1 and q2 represent an integer equal to at least 1 and such            that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150,        -   r represents a number such that 1≦r≦200        -   R₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₄, R₅, R₁₀ and R₁₁ represent hydrogen or the methyl or            ethyl radical        -   R₆, R₇, R₈ and R₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   R₁₂ represents a hydrocarbon radical having from 1 to 40            carbon atoms        -   A and B are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIb)

R-A-Si(OB)₃

-   -   where        -   R represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   A is a group which may be present, in which case it            represents a hydrocarbon radical having from 1 to 4 carbon            atoms        -   B represents a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIc)

-   -   where        -   m3, p3, m4 and p4 represent a number of alkylene oxide units            less than or equal to 150        -   n3 and n4 represent a number of ethylene oxide units less            than or equal to 150        -   q3 and q4 represent an integer equal to at least 1 and such            that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150,        -   r′ represents a number such that 1≦r′≦200,        -   R₁₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₁₄, R₁₅, R₂₀ and R₂₁ represent hydrogen or the methyl or            ethyl radical        -   R₁₆, R₁₇, R₁₈ and R₁₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   D and E are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,    -   d) possibly at least one monomer of the acrylamide or        methacrylamide type or their derivatives and mixtures thereof        such as N-[3-(dimethylamino) propyl]acrylamide or        N-[3-(dimethylamino) propyl]methacrylamide, and mixtures        thereof, or at least one non water-soluble monomer such as the        alkyl acrylates or methacrylates or mixtures thereof,        unsaturated esters such as        N-[2-(dimethylamino)ethyl]methacrylate, or        N-[2-(dimethylamino)ethyl]acrylate or mixtures thereof, vinyls        such as vinyl acetate, vinylpyrrolidone, styrene,        alphamethylstyrene and their derivatives or mixtures thereof, or        at least one cationic monomer or quaternary ammonium such as        [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [2-(acryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [3-(acrylamido) propyl]trimethyl ammonium chloride or        sulphate, dimethyl diallyl ammonium chloride or sulphate,        [3-(methacrylamido) propyl]trimethyl ammonium chloride or        sulphate, or mixtures thereof    -   e) possibly, at least one crosslinking monomer selected, but not        exclusively, from the group consisting of ethylene glycol        dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate,        the allyl maleates, methylene-bis-acrylamide,        methylene-bis-methacrylamide, tetrallyloxyethane,        triallylcyanurates, allyl ethers prepared from polyols such as        pentaerythritol, sorbitol, sucrose or others        the total of the components a), b), c), d) and e) being equal to        100%        and having an intrinsic viscosity less than or equal to 100 ml/g        measured in accordance with the above-mentioned method.

Another aim of the invention is to provide a grinding process in aqueoussuspension of mineral particles implementing said selected copolymers asa grinding agent.

Said copolymers implemented according to the invention furthermorepresent the advantage of reducing the formation of foam during thephysical operation, such as grinding and/or pumping and/or stirring ofmineral matter.

Moreover, another aim of the invention is to use said refined mineralaqueous suspensions as is or after drying in the field of paper, paintand plastics.

More particularly, another aim of the invention lies in using theserefined mineral aqueous suspensions for paper filling, and moreparticularly in applications known as “wet-end” applications, i.e.applications in processes for manufacturing paper, board or analogoussheet where they are used as filler, whether directly or indirectly.

Another aim also lies in the use of said refined mineral aqueoussuspensions in the treatment of the paper, board or analogous sheetwhere they are used as coating colour filler.

Another aim also lies in the use of said refined mineral aqueoussuspensions in the field of plastic, such as low density (LLDPE) andhigh density (HMW-HDPE) polyolefines, or breathable membranes, orpolyvinyl chlorides (PVC) and more particularly in the field of PVCssuch as rigid or flexible PVCs.

These goals are attained thanks to the use, as a grinding aid agent, ofa copolymer consisting of:

-   -   a) at least one ethylenically unsaturated anionic monomer having        a monocarboxyl function selected from among the ethylenically        unsaturated monomers having a monocarboxyl function such as        acrylic or methacrylic acid or hemiesters of diacids such as C₁        to C₄ monoesters of maleic or itaconic acid, or mixtures        thereof, or having a dicarboxyl function selected from among the        ethylenically unsaturated monomers having a dicarboxyl function        such as crotonic, isocrotonic, cinnamic, itaconic, maleic acid,        or anhydrides of carboxyl acids, such as maleic anhydride or        having a sulfonic function selected from among the ethylenically        unsaturated monomers having a sulfonic function such as        acrylamido-methyl-propane-sulfonic acid, sodium        methallylsulfonate, vinylsulfonic acid and styrenesulfonic acid        or having a phosphoric function selected from among the        ethylenically unsaturated monomers having a phosphoric function        such as vinylphosphoric acid, ethylene glycol methacrylate        phosphate, propylene glycol methacrylate phosphate, ethylene        glycol acrylate phosphate, propylene glycol acrylate phosphate        and their ethoxylates or having a phosphonic function selected        from among the ethylenically unsaturated monomers having a        phosphonic function such as vinylphosphonic acid, or mixtures        thereof,    -   b) at least one non-ionic ethylenically unsaturated monomer of        formula (I):

where

-   -   m and p represent a number of alkylene oxide units less than or        equal to 150    -   n represents a number of ethylene oxide units less than or equal        to 150    -   q represents an integer equal to at least 1 and such that        5≦(m+n+p)q≦150, and preferably represents an integer such that        15≦(m+n+p)q≦120,    -   R₁ represents hydrogen or the methyl or ethyl radical    -   R₂ represents hydrogen or the methyl or ethyl radical    -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R′ represents hydrogen or a hydrocarbon radical having from 1 to        40 carbon atoms, and preferably represents a hydrocarbon radical        having from 1 to 12 carbon atoms and even more preferably a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   or a mixture of several monomers of formula (I),    -   c) at least one organofluorinated or organosilylated monomer,        preferably selected from among the molecules of formulae (IIa)        or (IIb) or (IIc) or mixtures thereof:        with formula (IIa)

-   -   where        -   m1, p1, m2 and p2 represent a number of alkylene oxide units            less than or equal to 150        -   n1 and n2 represent a number of ethylene oxide units less            than or equal to 150        -   q1 and q2 represent an integer equal to at least 1 and such            that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150        -   r represents a number such that 1≦r≦200        -   R₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₄, R₅, R₁₀ and R₁₁ represent hydrogen or the methyl or            ethyl radical        -   R₆, R₇, R₈ and R₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   R₁₂ represents a hydrocarbon radical having from 1 to 40            carbon atoms        -   A and B are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIb)

R-A-Si(OB)₃

where

-   -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   A is a group which may be present, in which case it represents a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   B represents a hydrocarbon radical having from 1 to 4 carbon        atoms,        with formula (IIc)

-   -   where        -   m3, p3, m4 and p4 represent a number of alkylene oxide units            less than or equal to 150        -   n3 and n4 represent a number of ethylene oxide units less            than or equal to 150        -   q3 and q4 represent an integer equal to at least 1 and such            that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150,        -   r′ represents a number such that 1≦r′≦200,        -   R₁₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₁₄, R₁₅, R₂₀ and R₂₁ represent hydrogen or the methyl or            ethyl radical        -   R₁₆, R₁₇, R₁₈ and R₁₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   D and E are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,    -   d) possibly at least one monomer of the acrylamide or        methacrylamide type or their derivatives and mixtures thereof        such as N-[3-(dimethylamino) propyl]acrylamide or        N-[3-(dimethylamino) propyl]methacrylamide, and mixtures        thereof, or at least one non water-soluble monomer such as the        alkyl acrylates or methacrylates or mixtures thereof,        unsaturated esters such as        N-[2-(dimethylamino)ethyl]methacrylate, or        N-[2-(dimethylamino)ethyl]acrylate or mixtures thereof, vinyls        such as vinyl acetate, vinylpyrrolidone, styrene,        alphamethylstyrene and their derivatives or mixtures thereof, or        at least one cationic monomer or quaternary ammonium such as        [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [2-(acryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [3-(acrylamido) propyl]trimethyl ammonium chloride or        sulphate, dimethyl diallyl ammonium chloride or sulphate,        [3-(methacrylamido) propyl]trimethyl ammonium chloride or        sulphate, or mixtures thereof    -   e) possibly at least one crosslinking monomer selected, but not        exclusively, from the group consisting of ethylene glycol        dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate,        the allyl maleates, methylene-bis-acrylamide,        methylene-bis-methacrylamide, tetrallyloxyethane,        triallylcyanurates, allyl ethers prepared from polyols such as        pentaerythritol, sorbitol, sucrose or others        the total of the components a), b), c), d) and e) being equal to        100%.        and having an intrinsic viscosity less than or equal to 100 ml/g        measured in accordance with the above-mentioned method.

More particularly, the aqueous suspensions of refined mineral substancesaccording to the invention are characterized in that said copolymerconsists, by weight, of:

-   -   a) from 2% to 95%, preferably from 3% to 25%, and even more        preferably from 4% to 15%, of at least one ethylenically        unsaturated anionic monomer having a monocarboxyl function        selected from among the ethylenically unsaturated monomers        having a monocarboxyl function such as acrylic or methacrylic        acid or hemiesters of diacids such as C₁ to C₄ monoesters of        maleic or itaconic acid, or mixtures thereof, or having a        dicarboxyl function selected from among the ethylenically        unsaturated monomers having a dicarboxyl function such as        crotonic, isocrotonic, cinnamic, itaconic, maleic acid, or        anhydrides of carboxyl acids, such as maleic anhydride or having        a sulfonic function selected from among the ethylenically        unsaturated monomers having a sulfonic function such as        acrylamido-methyl-propane-sulfonic acid, sodium        methallylsulfonate, vinylsulfonic acid and styrenesulfonic acid        or having a phosphoric function selected from among the        ethylenically unsaturated monomers having a phosphoric function        such as vinylphosphoric acid, ethylene glycol methacrylate        phosphate, propylene glycol methacrylate phosphate, ethylene        glycol acrylate phosphate, propylene glycol acrylate phosphate        and their ethoxylates or having a phosphonic function selected        from among the ethylenically unsaturated monomers having a        phosphonic function such as vinylphosphonic acid, or mixtures        thereof,    -   b) From 97.9% to 4.9%, preferably from 95% to 65%, and even more        preferably from 92% to 78%, of at least one non-ionic        ethylenically unsaturated monomer of formula (I):

where

-   -   m and p represent a number of alkylene oxide units less than or        equal to 150    -   n represents a number of ethylene oxide units less than or equal        to 150    -   q represents an integer equal to at least 1 and such that        5≦(m+n+p)q≦150, and preferably represents an integer such that        15≦(m+n+p)q≦120,    -   R₁ represents hydrogen or the methyl or ethyl radical    -   R₂ represents hydrogen or the methyl or ethyl radical    -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R′ represents hydrogen or a hydrocarbon radical having from 1 to        40 carbon atoms, and preferably represents a hydrocarbon radical        having from 1 to 12 carbon atoms and even more preferably a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   or a mixture of several monomers of formula (I),    -   c) from 0.1% to 50%, preferably from 0.2% to 10%, and even more        preferably from 0.3% to 5%, of at least one organofluorinated or        organosilylated monomer, preferably selected from among the        molecules of formulae (IIa) or (IIb) or (IIc) or mixtures        thereof:        with formula (IIa)

-   -   where        -   m1, p1, m2 and p2 represent a number of alkylene oxide units            less than or equal to 150        -   n1 and n2 represent a number of ethylene oxide units less            than or equal to 150        -   q1 and q2 represent an integer equal to at least 1 and such            that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150,        -   r represents a number such that 1≦r≦200        -   R₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₄, R₅, R₁₀ and R₁₁ represent hydrogen or the methyl or            ethyl radical        -   R₆, R₇, R₈ and R₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   R₁₂ represents a hydrocarbon radical having from 1 to 40            carbon atoms        -   A and B are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIb)

R-A-Si(OB)₃

where

-   -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   A is a group which may be present, in which case it represents a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   B represents a hydrocarbon radical having from 1 to 4 carbon        atoms,        with formula (IIc)

-   -   where        -   m3, p3, m4 and p4 represent a number of alkylene oxide units            less than or equal to 150        -   n3 and n4 represent a number of ethylene oxide units less            than or equal to 150        -   q3 and q4 represent an integer equal to at least 1 and such            that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150,        -   r′ represents a number such that 1≦r′≦200,        -   R₁₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₁₄, R₁₅, R₂₀ and R₂₁ represent hydrogen or the methyl or            ethyl radical        -   R₁₆, R₁₇, R₁₈ and R₁₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof,        -   D and E are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,    -   d) from 0% to 50%, preferably from 0% to 10%, and even more        preferably from 0% to 5%, of at least one monomer of the        acrylamide or methacrylamide type or their derivatives and        mixtures thereof such as N-[3-(dimethylamino) propyl]acrylamide        or N-[3-(dimethylamino) propyl]methacrylamide, and mixtures        thereof, or at least one non water-soluble monomer such as the        alkyl acrylates or methacrylates or mixtures thereof,        unsaturated esters such as        N-[2-(dimethylamino)ethyl]methacrylate, or        N-[2-(dimethylamino)ethyl]acrylate or mixtures thereof, vinyls        such as vinyl acetate, vinylpyrrolidone, styrene,        alphamethylstyrene and their derivatives or mixtures thereof, or        at least one cationic monomer or quaternary ammonium such as        [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [2-(acryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [3-(acrylamido) propyl]trimethyl ammonium chloride or        sulphate, dimethyl diallyl ammonium chloride or sulphate,        [3-(methacrylamido) propyl]trimethyl ammonium chloride or        sulphate, or mixtures thereof    -   e) from 0% to 5%, preferably from 0% to 3%, of at least one        crosslinking monomer selected, but not exclusively, from the        group consisting of ethylene glycol dimethacrylate,        trimethylolpropanetriacrylate, allyl acrylate, the allyl        maleates, methylene-bis-acrylamide,        methylene-bis-methacrylamide, tetrallyloxyethane,        triallylcyanurates, allyl ethers prepared from polyols such as        pentaerythritol, sorbitol, sucrose or others        the total of the components a), b), c), d) and e) being equal to        100%,        and in that said copolymer has an intrinsic viscosity less than        or equal to 100 ml/g determined in accordance with the        above-mentioned method.

More particularly, the aqueous suspensions of mineral matter accordingto the invention are characterized in that they contain from 0.05% to10% of said co polymer by dry weight with respect to the dry weight ofmineral substances.

Equally particularly, the aqueous suspensions of mineral matteraccording to the invention are characterized in that said copolymer isin its acid form, or partially or fully neutralized by one or moreneutralizing agents.

These neutralizing agents are those that have a monovalent neutralizingfunction or a polyvalent neutralizing function such as, for example, forthe monovalent function those selected from the group consisting of thealkaline cations, in particular sodium, potassium, lithium, ammonium orthe primary, secondary or tertiary aliphatic and/or cyclic amines suchas for example stearylamine, the ethanolamines (mono-, di-,triethanolamine), mono and diethylamine, cyclohexylamine,methylcyclohexylamine, aminomethylpropanol, morpholine or, for thepolyvalent function, those selected from the group consisting ofalkaline earth divalent cations, in particular magnesium and calcium, orzinc, and of the trivalent cations, including in particular aluminium,or of certain cations of higher valency.

Another variant of the invention consists in the fact that the aqueoussuspensions of mineral matter according to the invention contain from0.05% to 10% of said copolymer by dry weight with respect to the dryweight of mineral substances and at least one other dispersant orgrinding aid agent.

Said other dispersant or grinding aid agent is then selected from thoseother dispersants or grinding agents familiar to the skilled man in theart such as, in particular, homopolymers or copolymers of acrylic acidin their acid forms, or fully or partially neutralized by one or moreneutralizing agents, said neutralizing agents being selected from thesame list as that referred to above, or is selected from among thedispersants or grinding aid agents such as, in particular, H₃O⁺ iondonors of which phosphoric acid and/or its salts with mono and/ordivalent bases such as soda or lime are particularly worthy of mention.

Specifically, the aqueous suspensions of mineral matter according to theinvention contain from 0.05% to 1% by dry weight with respect to the dryweight of mineral substances of said other dispersants or grinding aidagents.

Equally particularly, the aqueous suspensions of mineral matteraccording to the invention are characterized in that they have a drymatter content of between 15% and 85% by weight, and preferably between40% and 80%, and even more preferably between 50% and 78%.

In addition, the aqueous suspensions of mineral matter according to theinvention are characterized in that the mineral matter is selected fromamong calcium carbonate and various analogous fillers such as dolomite,gypsum, calcium hydroxide, satin white, titanium dioxide, aluminiumtrihydroxide or mixed carbonate based fillers of various metals such as,in particular, calcium associated with magnesium and analogues, variousmatter such as talc or analogues, and mixtures of these fillers such asfor example talc-calcium carbonate or calcium carbonate-kaolin mixtures,or mixtures of calcium carbonate with aluminium trihydroxide, thekaolins, calcine kaolins, mica or with synthetic or natural fibres orco-structures of minerals such as talc-calcium carbonate ortalc-titanium dioxide co-structures.

Preferably, the aqueous suspensions of mineral matter according to theinvention are characterized in that the mineral matter consists ofcalcium carbonate such as natural calcium carbonate selected from amongmarble, calcite, chalk or mixtures thereof.

These aqueous suspensions of mineral matter according to the inventionare also characterized in that the mineral matter presents a mediangrain diameter, measured using the Sedigraph™ 5100, of between 50 μm and0.1 μm, preferably between 5 μm and 0.2 μm and even more preferablybetween 2 μm and 0.5 μm.

These aqueous suspensions of mineral matter according to the inventionare also characterized in that they have a pH of between 7.5 and 13,preferably between 8 and 12, and even more preferably between 8.5 and10.

The use, according to the invention, of a copolymer as a grinding aidagent for mineral matter in aqueous suspension, is characterized in thatsaid copolymer consists of:

-   -   a) at least one ethylenically unsaturated anionic monomer having        a monocarboxyl function selected from among the ethylenically        unsaturated monomers having a monocarboxyl function such as        acrylic or methacrylic acid or hemiesters of diacids such as C₁        to C₄ monoesters of maleic or itaconic acid, or mixtures        thereof, or having a dicarboxyl function selected from among the        ethylenically unsaturated monomers having a dicarboxyl function        such as crotonic, isocrotonic, cinnamic, itaconic, maleic acid,        or anhydrides of carboxyl acids, such as maleic anhydride or        having a sulfonic function selected from among the ethylenically        unsaturated monomers having a sulfonic function such as        acrylamido-methyl-propane-sulfonic acid, sodium        methallylsulfonate, vinylsulfonic acid and styrenesulfonic acid        or having a phosphoric function selected from among the        ethylenically unsaturated monomers having a phosphoric function        such as vinylphosphoric acid, ethylene glycol methacrylate        phosphate, propylene glycol methacrylate phosphate, ethylene        glycol acrylate phosphate, propylene glycol acrylate phosphate        and their ethoxylates or having a phosphonic function selected        from among the ethylenically unsaturated monomers having a        phosphonic function such as vinylphosphonic acid, or mixtures        thereof,    -   b) at least one non-ionic ethylenically unsaturated monomer of        formula (I):

where

-   -   m and p represent a number of alkylene oxide units less than or        equal to 150    -   n represents a number of ethylene oxide units less than or equal        to 150    -   q represents an integer equal to at least 1 and such that        5≦(m+n+p)q≦150, and preferably represents an integer such that        15≦(m+n+p)q≦120,    -   R₁ represents hydrogen or the methyl or ethyl radical    -   R₂ represents hydrogen or the methyl or ethyl radical    -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R′ represents hydrogen or a hydrocarbon radical having from 1 to        40 carbon atoms, and preferably represents a hydrocarbon radical        having from 1 to 12 carbon atoms and even more preferably a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   or a mixture of several monomers of formula (I),    -   c) at least one organofluorinated or organosilylated monomer,        preferably selected from among the molecules of formulae (IIa)        or (IIb) or (IIc) or mixtures thereof:        with formula (IIa)

-   -   where        -   m1, p1, m2 and p2 represent a number of alkylene oxide units            less than or equal to 150        -   n1 and n2 represent a number of ethylene oxide units less            than or equal to 150        -   q1 and q2 represent an integer equal to at least 1 and such            that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150,        -   r represents a number such that 1≦r≦200        -   R₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₄, R₅, R₁₀ and R₁₁ represent hydrogen or the methyl or            ethyl radical        -   R₆, R₇, R₈ and R₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   R₁₂ represents a hydrocarbon radical having from 1 to 40            carbon atoms        -   A and B are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIb)

R-A-Si(OB)₃

where

-   -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   A is a group which may be present, in which case it represents a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   B represents a hydrocarbon radical having from 1 to 4 carbon        atoms,        with formula (IIc)

-   -   where        -   m3, p3, m4 and p4 represent a number of alkylene oxide units            less than or equal to 150        -   n3 and n4 represent a number of ethylene oxide units less            than or equal to 150        -   q3 and q4 represent an integer equal to at least 1 and such            that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150,        -   r′ represents a number such that 1≦r′≦200,        -   R₁₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₁₄, R₁₅, R₂₀ and R₂₁ represent hydrogen or the methyl or            ethyl radical        -   R₁₆, R₁₇, R₁₈ and R₁₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   D and E are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,    -   d) possibly at least one monomer of the acrylamide or        methacrylamide type or their derivatives and mixtures thereof        such as N-[3-(dimethylamino) propyl]acrylamide or        N-[3-(dimethylamino) propyl]methacrylamide, and mixtures        thereof, or at least one non water-soluble monomer such as the        alkyl acrylates or methacrylates or mixtures thereof,        unsaturated esters such as        N-[2-(dimethylamino)ethyl]methacrylate, or        N-[2-(dimethylamino)ethyl]acrylate or mixtures thereof, vinyls        such as vinyl acetate, vinylpyrrolidone, styrene,        alphamethylstyrene and their derivatives or mixtures thereof, or        at least one cationic monomer or quaternary ammonium such as        [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [2-(acryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [3-(acrylamido) propyl]trimethyl ammonium chloride or        sulphate, dimethyl diallyl ammonium chloride or sulphate,        [3-(methacrylamido) propyl]trimethyl ammonium chloride or        sulphate, or mixtures thereof    -   e) possibly at least one crosslinking monomer selected, but not        exclusively, from the group consisting of ethylene glycol        dimethacrylate, trimethylolpropanetriacrylate, allyl acrylate,        the allyl maleates, methylene-bis-acrylamide,        methylene-bis-methacrylamide, tetrallyloxyethane,        triallylcyanurates, allyl ethers prepared from polyols such as        pentaerythritol, sorbitol, sucrose or others        the total of the components a), b), c), d) and e) being equal to        100%.        and in that said copolymer has an intrinsic viscosity less than        or equal to 100 ml/g determined in accordance with the        above-mentioned method.

More particularly, the use of the above-mentioned copolymer ischaracterized in that said copolymer consists, in terms of weight, of:

-   -   a) from 2% to 95%, preferably from 3% to 25%, and even more        preferably from 4% to 15%, of at least one ethylenically        unsaturated anionic monomer having a monocarboxyl function        selected from among the ethylenically unsaturated monomers        having a monocarboxyl function such as acrylic or methacrylic        acid or hemiesters of diacids such as C₁ to C₄ monoesters of        maleic or itaconic acid, or mixtures thereof, or having a        dicarboxyl function selected from among the ethylenically        unsaturated monomers having a dicarboxyl function such as        crotonic, isocrotonic, cinnamic, itaconic, maleic acid, or        anhydrides of carboxyl acids, such as maleic anhydride or having        a sulfonic function selected from among the ethylenically        unsaturated monomers having a sulfonic function such as        acrylamido-methyl-propane-sulfonic acid, sodium        methallylsulfonate, vinylsulfonic acid and styrenesulfonic acid        or having a phosphoric function selected from among the        ethylenically unsaturated monomers having a phosphoric function        such as vinylphosphoric acid, ethylene glycol methacrylate        phosphate, propylene glycol methacrylate phosphate, ethylene        glycol acrylate phosphate, propylene glycol acrylate phosphate        and their ethoxylates or having a phosphonic function selected        from among the ethylenically unsaturated monomers having a        phosphonic function such as vinylphosphonic acid, or mixtures        thereof,    -   b) From 97.9% to 4.9%, preferably from 95% to 65%, and even more        preferably from 92% to 78%, of at least one non-ionic        ethylenically unsaturated monomer of formula (I):

where

-   -   m and p represent a number of alkylene oxide units less than or        equal to 150    -   n represents a number of ethylene oxide units less than or equal        to 150    -   q represents an integer equal to at least 1 and such that        5≦(m+n+p)q≦150, and preferably represents an integer such that        15≦(m+n+p)q≦120,    -   R₁ represents hydrogen or the methyl or ethyl radical    -   R₂ represents hydrogen or the methyl or ethyl radical    -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   R′ represents hydrogen or a hydrocarbon radical having from 1 to        40 carbon atoms, and preferably represents a hydrocarbon radical        having from 1 to 12 carbon atoms and even more preferably a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   or a mixture of several monomers of formula (I),    -   c) from 0.1% to 50%, preferably from 0.2% to 10%, and even more        preferably from 0.3% to 5%, of at least one organofluorinated or        organosilylated monomer, preferably selected from among the        molecules of formulae (IIa) or (IIb) or (IIc) or mixtures        thereof:        with formula (IIa)

-   -   where        -   m1, p1, m2 and p2 represent a number of alkylene oxide units            less than or equal to 150        -   n1 and n2 represent a number of ethylene oxide units less            than or equal to 150        -   q1 and q2 represent an integer equal to at least 1 and such            that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150,        -   r represents a number such that 1≦r≦200        -   R₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₄, R₅, R₁₀ and R₁₁ represent hydrogen or the methyl or            ethyl radical        -   R₆, R₇, R₈ and R₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   R₁₂ represents a hydrocarbon radical having from 1 to 40            carbon atoms        -   A and B are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,            with formula (IIb)

R-A-Si(OB)₃

where

-   -   R represents a radical containing a polymerizable unsaturated        function, preferably belonging to the vinyl group and to the        group of acrylic, methacrylic, maleic, itaconic, crotonic, and        vinylphtalic esters and to the group of urethane unsaturates        such as for example acrylurethane, methacrylurethane, α-α′        dimethyl-isopropenyl-benzylurethane and allylurethane, and to        the group of allyl or vinyl ethers, whether or not substituted,        or to the group of ethylenically unsaturated amides or imides,    -   A is a group which may be present, in which case it represents a        hydrocarbon radical having from 1 to 4 carbon atoms,    -   B represents a hydrocarbon radical having from 1 to 4 carbon        atoms,        with formula (IIc)

-   -   where        -   m3, p3, m4 and p4 represent a number of alkylene oxide units            less than or equal to 150        -   n3 and n4 represent a number of ethylene oxide units less            than or equal to 150        -   q3 and q4 represent an integer equal to at least 1 and such            that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150,        -   r′ represents a number such that 1≦r′≦200,        -   R₁₃ represents a radical containing a polymerizable            unsaturated function, preferably belonging to the vinyl            group and to the group of acrylic, methacrylic, maleic,            itaconic, crotonic, and vinylphtalic esters and to the group            of urethane unsaturates such as for example acrylurethane,            methacrylurethane, α-α′ dimethyl-isopropenyl-benzylurethane            and allylurethane, and to the group of allyl or vinyl            ethers, whether or not substituted, or to the group of            ethylenically unsaturated amides or imides,        -   R₁₄, R₁₅, R₂₀ and R₂₁ represent hydrogen or the methyl or            ethyl radical        -   R₁₆, R₁₇, R₁₈ and R₁₉ represent straight or branched alkyl,            aryl, alkylaryl or arylalkyl groups having from 1 to 20            carbon atoms, or a mixture thereof        -   D and E are groups which may be present, in which case they            represent a hydrocarbon radical having from 1 to 4 carbon            atoms,    -   d) from 0% to 50%, preferably from 0% to 10%, and even more        preferably from 0% to 5%, of at least one monomer of the        acrylamide or methacrylamide type or their derivatives or        mixtures thereof such as N-[3-(dimethylamino) propyl]acrylamide        or N-[3-(dimethylamino) propyl]methacrylamide, and mixtures        thereof, or at least one non water-soluble monomer such as the        alkyl acrylates or methacrylates or mixtures thereof,        unsaturated esters such as        N-[2-(dimethylamino)ethyl]methacrylate, or        N-[2-(dimethylamino)ethyl]acrylate or mixtures thereof, vinyls        such as vinyl acetate, vinylpyrrolidone, styrene,        alphamethylstyrene and their derivatives or mixtures thereof, or        at least one cationic monomer or quaternary ammonium such as        [2-(methacryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [2-(acryloyloxy)ethyl]trimethyl ammonium chloride or        sulphate, [3-(acrylamido) propyl]trimethyl ammonium chloride or        sulphate, dimethyl diallyl ammonium chloride or sulphate,        [3-(methacrylamido) propyl]trimethyl ammonium chloride or        sulphate, or mixtures thereof    -   e) from 0% to 5%, preferably from 0% to 3%, of at least one        crosslinking monomer selected, but not exclusively, from the        group consisting of ethylene glycol dimethacrylate,        trimethylolpropanetriacrylate, allyl acrylate, the allyl        maleates, methylene-bis-acrylamide,        methylene-bis-methacrylamide, tetrallyloxyethane,        triallylcyanurates, allyl ethers prepared from polyols such as        pentaerythritol, sorbitol, sucrose or others.        the total of the components a), b), c), d) and e) being equal to        100%,        and in that said copolymer has an intrinsic viscosity less than        or equal to 100 ml/g determined in accordance with the        above-mentioned method.

The copolymer used according to the invention is obtained by knownradical copolymerization processes in solution, in direct or inverseemulsion, in suspension or precipitation in appropriate solvents, in thepresence of known catalytic systems and transfer agents, or by means ofcontrolled radical polymerization processes such as the method known asReversible Addition Fragmentation Transfer (RAFT), the method known asAtom Transfer Radical Polymerization (ATRP), the method known asNitroxide Mediated Polymerization (NMP), or the method known asCobaloxime Mediated Free Radical Polymerization.

This copolymer obtained in acid form and possibly distilled can also befully or partially neutralized using one or more neutralizing agentshaving a monovalent neutralizing function or a polyvalent neutralizingfunction such as, for example, for the monovalent function thoseselected from the group consisting of the alkaline cations, inparticular sodium, potassium, lithium, ammonium or the primary,secondary or tertiary aliphatic and/or cyclic amines such as for examplestearylamine, the ethanolamines (mono-, di-, triethanolamine), mono anddiethylamine, cyclohexylamine, methylcyclohexylamine,aminomethylpropanol, morpholine or, for the polyvalent function thoseselected from the group consisting of alkaline-earth divalent cations,in particular magnesium and calcium, or zinc, and of the trivalentcations, including in particular aluminium, or of certain cations ofhigher valency.

Each neutralizing agent then operates according to neutralization ratesproper to each valency function.

According to another variant, the copolymer obtained from thecopolymerization reaction may, before or after the total or partialneutralization reaction, be treated and separated into several phases,according to statistical or dynamic processes known to the skilled manin the art, by one or more polar solvents belonging to the groupconsisting of water, methanol, ethanol, propanol, isopropanol, butanols,acetone, tetrahydrofurane or mixtures thereof.

One of the phases then corresponds to the copolymer used according tothe invention as dispersing agent or grinding aid agent of mineralmatter in aqueous suspension.

The invention also relates to said weakly ionic and water-solublegrinding aid agent of mineral substances in aqueous suspension havingthe property of being weakly charged. Said agent is characterized inthat it is the above-described copolymer.

The invention also relates to the grinding process that implements saidgrinding aid agent of mineral substances in aqueous suspension.

In practice, according to the invention, grinding the mineral substanceconsists in refining said substance into very fine particles using agrinding body in an aqueous environment by means of the copolymer usedas a grinding aid agent.

A variant consists in forming, by introducing the total quantity of thecopolymer, an aqueous suspension of the mineral substance to be ground,the particles of which have an initial dimension equal to no more than50 micrometres.

To the suspension of the mineral substance to be ground thus formed isadded the grinding body of a grain size preferably between 0.20millimetres and 4 millimetres. The grinding body is generally presentedin the form of particles of materials as diverse as silicium oxide,aluminium oxide, zirconium oxide or mixtures thereof together withsynthetic resins of great hardness, steels or others.

The grinding body is preferably added to the suspension in a quantitysuch that the ratio by weight between this material and the mineralsubstance to be ground is at least 2/1, this ratio preferably beingbetween the limits 3/1 and 5/1.

The mixture of the suspension and the grinding body is then subjected tomechanical grinding action, such as that which occurs in a classicalmicroelement grinder.

The quantity of grinding aid agent introduced varies from 0.05% to 10%by dry weight of said copolymers with respect to the dry mass of themineral substance to be refined.

The time necessary to obtain a highly refined mineral substance aftergrinding varies according to the nature and quantity of the mineralsubstances to be refined and according to the stirring mode used and thetemperature of the medium during the grinding operation.

Another variant consists in using a part of the grinding aid agentbefore the grinding stage and implementing the rest of the quantity ofthe grinding agent during the grinding operation.

Finally, another variant consists in not implementing the copolymerbefore the grinding stage and using the entire quantity necessary duringthe grinding operation, which takes place in one or more stages.

Thus, according to the invention, the grinding process in aqueoussuspension intended for pigmentary applications consisting in refininginto very fine particles an aqueous suspension of said mineral materialsis characterized in that use is made, as a grinding aid agent, of 0.05%to 10% by dry weight of the above-mentioned polymers with respect to thedry weight of mineral materials before and/or during the grinding stage.

Another mode of implementing the invention also consists inimplementing, in addition to said copolymer used as a grinding agent, atleast one other grinding agent before and/or during the grinding stage.

Thus, according to a variant, the grinding process according to theinvention is characterized in that use is made, as a grinding aid agent,of 0.05% to 10% by dry weight of the above-mentioned polymers withrespect to the dry weight of mineral materials and at least one otherdispersant or grinding aid agent before and/or during the grindingstage.

Said other dispersant or grinding aid agent is then selected from thoseother dispersants or grinding aid agents familiar to the skilled man inthe art such as, in particular, homopolymers or copolymers of acrylicacid in their acid forms, or fully or partially neutralized by one ormore neutralizing agents, said neutralizing agents being selected fromthe same list as that referred to above, or is selected from among thedispersants or grinding aid agents such as, in particular, H₃O⁺ iondonors of which phosphoric acid and/or its salts with mono and/ordivalent bases such as soda or lime are particularly worthy of mention.

Particularly, the grinding process according to the invention ischaracterized in that use is made of 0.05% to 1.0%, by dry weight withrespect to the dry weight of mineral substances, of said otherdispersant or grinding aid agent.

The temperature during the course of the grinding stage and for all thevariants of the grinding process according to the invention lies between15° C. and 150° C., preferably between 50° C. and 105° C. and especiallypreferably between 60° C. and 98° C.

For mineral matter containing carbonate, the pH during the course of thegrinding stage and for all the variants of the grinding processaccording to the invention lies between 6 and 13, preferably between 7.5and 12 and especially preferably between 8 and 10.

For mineral matter not containing carbonate, the pH during the course ofthe grinding stage and for all the variants of the grinding processaccording to the invention lies between 2 and 13, preferably between 7.5and 12 and especially preferably between 8 and 10.

When implementing these various grinding variants, apart from theproblem that it resolves, the invention has the advantage that less foamis produced during grinding when using the copolymers than when usingthe polymers of the prior art. Another advantage of the inventionconsists in the fact that the aqueous suspensions of mineral matterrefined according to the invention always have grains of mineral matterhaving, for an equivalent grain size, a specific surface area less thanthe grains of mineral matter of the aqueous suspensions of mineralmatter refined according to the prior art by implementing polyacrylate.This advantage is perceptible when the end user uses latex in coatingformulations.

Thus the aqueous suspensions of mineral matter according to theinvention are characterized in that the grains of mineral matter have,for an equivalent grain size, a BET specific surface area less than thegrains of mineral matter of the aqueous suspensions of mineral matterrefined using grinding aid agents such as polyacrylates, homopolymers orcopolymers well known to the skilled man in the art.

The mineral substances to be refined according to the process of theinvention can be of highly diverse origin such as calcium carbonate,dolomites, kaolins, calcine kaolins, talc, gypsum, titanium oxide, oraluminium trihydroxide or any other filler and/or pigment that has to beground in order to be used in applications such as the manufacture ofpapers, board or analogues and are preferably calcium carbonate such asnatural calcium carbonate selected from among marble, calcite, chalk ormixtures thereof.

The papers manufactured according to the invention are characterized inthat they contain said aqueous suspensions of fillers and/or pigmentsaccording to the invention.

The scope and interest of the invention will be better perceived thanksto the following examples, which are not of a comprehensive nature.

EXAMPLE 1

This example illustrates, by comparison with comparable grain size, howto reduce the cationic polymer demand in the mass by implementing anaqueous suspension of calcium carbonate containing the copolymer used,according to the invention, as a grinding aid agent.

Test No. 1

This test illustrates the prior art and implements 0.27% by dry weight,with respect to the dry weight of calcium carbonate, of a sodium andmagnesium polyacrylate of intrinsic viscosity equal to 7.8 ml/gaccording to the above-mentioned intrinsic viscosity method, to obtain,from a calcium carbonate with a median diameter of 15 μm, an aqueoussuspension of ground calcium carbonate having a dry matter concentrationequal to 65.5% by weight and having a grain size such that 61% by weightof the particles have a diameter of less than 2 μm, and 30% by weight ofthe particles have a diameter of less than 1 μm measured on theSedigraph™ 5100 corresponding to a median diameter equal to 1.63 μm.

To do this, use is made of a Dyno-Mill™ type fixed-cylinder grinder withrotating impeller, the grinding body of which consists of zirconiumbased beads of a diameter between 0.6 millimetres and 1 millimetre.

The total volume occupied by the grinding body is 1000 cubic centimetreswhile its weight is 2700 g.

The grinding chamber has a volume of 1400 cubic centimetres.

The circumferential speed of the grinder is 10 metres per second.

The pigment suspension is recycled at a rate of 40 litres per hour.

The output of the Dyno-Mill is fitted with a 200-micron grade separatorby means of which it is possible to separate the suspension that resultsfrom the grinding and the grinding body.

The temperature during each grinding test is maintained at approximately60° C.

One hour after grinding is completed, a sample of the pigmentarysuspension, the grain size of which (% of particles less than 2micrometres) is measured using a Sedigraph™ 5100 particle size analyzer,is recovered in a beaker.

The Brookfield™ viscosity of the suspension is measured using a modelRVT Brookfield™ viscometer, at a temperature of 23° C. and a rotationspeed of 100 rpm with the appropriate 3 spindle.

Having left this sample lie in the beaker for 7 days, the Brookfield™viscosity of the suspension is measured by introducing, into theunstirred beaker, the appropriate spindle of the RVT model Brookfield™viscometer, at a temperature of 23° C. and a rotation speed of 100 rpm.(AVAG viscosity=viscosity before stirring).

The same Brookfield™ viscosity measurements are also made once thebeaker has been stirred for 5 minutes and constitute the APAG (afterstirring) viscosity results.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained are as follows:

S.C.=65.5%

Viscosity (T₀)=115 mPa·sAVAG viscosity (T_(7 days))=620 mPa·sAPAG viscosity (T_(7 days))=155 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined.

The BET specific surface area, determined according to standard ISO9277, is equal to 7.2 m²/g

The PDDPC cationic polymer demand, measured using the Mettler DL77titrator and the Mütec PCD 02 detector using the cationic titrationmethod implementing 0.005 mole of a solution of 20% ofpoly(N,N-dimethyl-3,5-dimethylene-piperidinium chloride (PDDPC) sold byAcros Organics is equal to 12100 μVal/kg, this value being the valuecorresponding to zero charge of the detector used.

Test No. 2

This test illustrates the prior art and implements 0.47% by dry weight,with respect to the dry weight of calcium carbonate, of a sodium andmagnesium polyacrylate of intrinsic viscosity equal to 7.8 ml/gaccording to the above-mentioned intrinsic viscosity method, to obtain,from a calcium carbonate with a median diameter of 15 μm, and under thesame operating conditions and using the same equipment as in test No. 1,an aqueous suspension of ground calcium carbonate having a dry matterconcentration equal to 75% by weight and having a grain size such that90% by weight of the particles have a diameter of less than 2 μm asmeasured on the Sedigraph™ 5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=75.8%

Viscosity (T₀)=265 mPa·sAVAG viscosity (T_(7 days))=726 mPa·sAPAG viscosity (T_(7 days))=278 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 12.0 m²/g and a PDDPCcationic polymer demand equal to 20220 μVal/kg.

Test No. 3

This test illustrates the prior art and implements 0.79% by dry weight,with respect to the dry weight of calcium carbonate, of a sodium andmagnesium polyacrylate of intrinsic viscosity equal to 7.8 ml/gaccording to the above-mentioned intrinsic viscosity method, to obtain,from a calcium carbonate with a median diameter of 15 μm, and under thesame operating conditions and using the same equipment as in test No. 1,an aqueous suspension of ground calcium carbonate having a dry matterconcentration equal to 76.5% by weight and having a grain size such that78% by weight of the particles have a diameter of less than 1 μm asmeasured on the Sedigraph™ 5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=77.1%

Viscosity (T₀)=371 mPa·sAVAG viscosity (T_(7 days))=886 mPa·sAPAG viscosity (T_(7 days))=412 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 16.2 m²/g and a PDDPCcationic polymer demand equal to 33990 μVal/kg.

Test No. 4

This test illustrates the prior art and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of a copolymerconsisting, by weight, of:

-   -   14% acrylic acid    -   3% methacrylic acid    -   83% of polyethylene glycol methacrylate with a molecular weight        of 2000 of intrinsic viscosity equal to 20.0 ml/g according to        the above-mentioned intrinsic viscosity method, to obtain, from        a calcium carbonate with a median diameter of 15 μm, and under        the same operating conditions and using the same equipment as in        test No. 1, an aqueous suspension of ground calcium carbonate        having a dry matter concentration equal to 75% by weight and        having a grain size such that 57% by weight of the particles        have a diameter of less than 2 μm measured on the Sedigraph™        5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=71.3%

Viscosity (T₀)=158 mPa·sAVAG viscosity (T_(7 days))=677 mPa·sAPAG viscosity (T_(7 days))=254 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 4.9 m²/g and a PDDPCcationic polymer demand equal to 3100 μVal/kg.

Test No. 5

This test illustrates the prior art and implements 1.17% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 4 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 87% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=72.0%

Viscosity (T₀)=224 mPa·sAVAG viscosity (T_(7 days))=987 mPa·sAPAG viscosity (T_(7 days))=248 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 9.6 m²/g and a PDDPCcationic polymer demand equal to 10000 μVal/kg.

In this test, a measurement was made of the foam by measuring the time acertain height of foam (height h in cm) took to form and the timenecessary for this foam to disappear (t_(disp)).

-   -   In this test, t=90 seconds for h=23 cm and t_(disp)=5 minutes.

Test No. 6

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of a copolymerconsisting, by weight, of:

-   -   a) 3.0% acrylic acid and 2.0% maleic acid    -   b) 94.0% of a monomer of formula (I) in which:        -   R₁ represents hydrogen        -   R₂ represents hydrogen        -   R represents the vinyl group        -   R′ represents the methyl radical        -   where m=p=0; n=114; q=1 and (m+n+p)q=114    -   c) 1.0% of a monomer of formula (IIb) in which        -   R represents the methacrylate group        -   A represents the propyl radical        -   B represents the methyl radical            of intrinsic viscosity equal to 39.5 ml/g according to the            above-mentioned intrinsic viscosity method (and equal to            30.3 ml/g according to the second method), to obtain, from a            calcium carbonate with a median diameter of 15 μm, and under            the same operating conditions and using the same equipment            as in test No. 1, an aqueous suspension of ground calcium            carbonate having a dry matter concentration equal to 75% by            weight and having a grain size such that 59% by weight of            the particles have a diameter of less than 2 μm measured on            the Sedigraph™ 5100 corresponding to a median diameter equal            to 1.41 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=75.2%

Viscosity (T₀)=125 mPa·sAVAG viscosity (T_(7 days))=338 mPa·sAPAG viscosity (T_(7 days))=127 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 4.8 m²/g and a PDDPCcationic polymer demand equal to 590 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=600 seconds for h=6 cm and t_(disp)=immediate.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 7

This test illustrates the invention and implements 1.07% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 90% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™5100, corresponding to a median diameter equal to 0.83 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=75.4%

Viscosity (T₀)=241 mPa·sAVAG viscosity (T_(7 days))=359 mPa·sAPAG viscosity (T_(7 days))=241 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 6.8 m²/g and a PDDPCcationic polymer demand equal to 2340 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=600 seconds for h=6 cm and t_(disp)=immediate.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 8

This test illustrates the invention and implements 2.10% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 80% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100, corresponding to a median diameter equal to 0.55 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=75.0%

Viscosity (T₀)=717 mPa·sAVAG viscosity (T_(7 days))=1570 mPa·sAPAG viscosity (T_(7 days))=697 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 8.4 m²/g and a PDDPCcationic polymer demand equal to 4590 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=600 seconds for h=6 cm and t_(disp)=immediate.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 9

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of a copolymerconsisting, by weight, of:

-   -   a) 8.7% acrylic acid and 1.5% methacrylic acid    -   b) 89.4% of a monomer of formula (I) in which:        -   R₁ represents hydrogen        -   R₂ represents hydrogen        -   R represents the methacrylate group        -   R′ represents the methyl radical        -   where m=p=0; n=114; q=1 and (m+n+p)q=114    -   c) 0.4% of a monomer of formula (IIb) in which        -   R represents the methacrylate group        -   A represents the propyl radical        -   B represents the methyl radical            of intrinsic viscosity equal to 20.7 ml/g according to the            above-mentioned intrinsic viscosity method, to obtain, from            a calcium carbonate with a median diameter of 15 μm, and            under the same operating conditions and using the same            equipment as in test No. 1, an aqueous suspension of ground            calcium carbonate having a dry matter concentration equal to            75% by weight and having a grain size such that 58% by            weight of the particles have a diameter of less than 2 μm            measured on the Sedigraph™ 5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=71.9%

Viscosity (T₀)=138 mPa·sAVAG viscosity (T_(7 days))=486 mPa·sAPAG viscosity (T_(7 days))=159 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 4.8 m²/g and a PDDPCcationic polymer demand equal to 340 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=510 seconds for h=23 cmt_(disp)=2 minutes.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 10

This test illustrates the invention and implements 1.10% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 9 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 89% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=73.5%

Viscosity (T₀)=164 mPa·sAVAG viscosity (T_(7 days))=593 mPa·sAPAG viscosity (T_(7 days))=175 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 7.8 m²/g and a PDDPCcationic polymer demand equal to 2770 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=510 seconds for h=23 cm and t_(disp)=2 minutes.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 11

This test illustrates the invention and implements 2.08% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 9 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 81% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=74.7%

Viscosity (T₀)=712 mPa·sAVAG viscosity (T_(7 days))=2240 mPa·sAPAG viscosity (T_(7 days))=686 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 4.8 m²/g and a PDDPCcationic polymer demand equal to 7050 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=510 seconds for h=23 cm and t_(disp)=2 minutes.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 12

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of a copolymerconsisting, by weight, of:

-   -   a) 8.7% acrylic acid and 1.5% methacrylic acid    -   b) 89.5% of a monomer of formula (I) in which:        -   R₁ represents hydrogen        -   R₂ represents hydrogen        -   R represents the methacrylate group        -   R′ represents the methyl radical        -   where m=p=0; n=114; q=1 and (m+n+p)q=114    -   c) 0.3% of a monomer of formula (IIb) in which        -   R represents the vinyl group        -   A is absent        -   B represents the methyl radical            of intrinsic viscosity equal to 20.4 ml/g according to the            above-mentioned intrinsic viscosity method, to obtain, from            a calcium carbonate with a median diameter of 15 μm, and            under the same operating conditions and using the same            equipment as in test No. 1, an aqueous suspension of ground            calcium carbonate having a dry matter concentration equal to            75% by weight and having a grain size such that 58% by            weight of the particles have a diameter of less than 2 μm            measured on the Sedigraph™ 5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=73.0%

Viscosity (T₀)=144 mPa·sAVAG viscosity (T_(7 days))=628 mPa·sAPAG viscosity (T_(7 days))=171 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 4.8 m²/g and a PDDPCcationic polymer demand equal to 880 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=180 seconds for h=23 cm and t_(disp)=3 minutes.

These results show that less foam is created than in the test of theprior art.

Test No. 13

This test illustrates the invention and implements 1.10% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 12 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 90% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=73.1%

Viscosity (T₀)=195 mPa·sAVAG viscosity (T_(7 days))=731 mPa·sAPAG viscosity (T_(7 days))=185 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 8.1 m²/g and a PDDPCcationic polymer demand equal to 3760 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=180 seconds for h=23 cm and t_(disp)=3 minutes.

These results show that less foam is created than in the test of theprior art.

Test No. 14

This test illustrates the invention and implements 2.10% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 12 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 83% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=74.3%

Viscosity (T₀)=613 mPa·sAVAG viscosity (T_(7 days))=3030 mPa·sAPAG viscosity (T_(7 days))=650 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 11.1 m²/g and a PDDPCcationic polymer demand equal to 7180 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=180 seconds for h=23 cm and t_(disp)=3 minutes.

These results show that less foam is created than in the test of theprior art.

Test No. 15

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of a copolymerconsisting, by weight, of:

-   -   a) 8.5% acrylic acid and 1.5% methacrylic acid    -   b) 87.0% of a monomer of formula (I) in which:        -   R₁ represents hydrogen        -   R₂ represents hydrogen        -   R represents the methacrylate group        -   R′ represents the methyl radical        -   where m=p=0; n=114; q=1 and (m+n+p)q=114    -   c) 3.0% of a monomer of formula (IIb) in which        -   R represents the methacrylate group        -   A represents the propyl radical        -   B represents the methyl radical            of intrinsic viscosity equal to 23.2 ml/g according to the            above-mentioned intrinsic viscosity method, to obtain, from            a calcium carbonate with a median diameter of 15 μm, and            under the same operating conditions and using the same            equipment as in test No. 1, an aqueous suspension of ground            calcium carbonate having a dry matter concentration equal to            75% by weight and having a grain size such that 58% by            weight of the particles have a diameter of less than 2 μm as            measured on the Sedigraph™ 5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=73.7%

Viscosity (T₀)=156 mPa·sAVAG viscosity (T_(7 days))=733 mPa·sAPAG viscosity (T_(7 days))=197 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 4.9 m²/g and a PDDPCcationic polymer demand equal to 1280 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=150 seconds for h=23 cm and t_(disp)=4 minutes.

These results show that less foam is created than in the test of theprior art.

Test No. 16

This test illustrates the invention and implements 1.25% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 15 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 87% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=75.9%

Viscosity (T₀)=196 mPa·sAVAG viscosity (T_(7 days))=642 mPa·sAPAG viscosity (T_(7 days))=189 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 7.6 m²/g and a PDDPCcationic polymer demand equal to 4150 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=150 seconds for h=23 cm and t_(disp)=4 minutes.

These results show that less foam is created than in the test of theprior art.

Test No. 17

This test illustrates the invention and implements 2.08% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 15 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 81% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=77.0%

Viscosity (T₀)=648 mPa·sAVAG viscosity (T_(7 days))=2840 mPa·sAPAG viscosity (T_(7 days))=747 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area equal to 9.3 m²/g and a PDDPCcationic polymer demand equal to 6900 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=150 seconds for h=23 cm and t_(disp)=4 minutes.

These results show that less foam is created than in the test of theprior art.

Test No. 18

This test illustrates the invention and implements 0.79% by dry weight,with respect to the dry weight of calcium carbonate, of a copolymerconsisting, by weight, of:

-   -   a) 8.5% acrylic acid and 1.5% methacrylic acid    -   b) 87.0% of a monomer of formula (I) in which:        -   R₁ represents hydrogen        -   R₂ represents hydrogen        -   R represents the methacrylate group        -   R′ represents the methyl radical        -   where m=p=0; n=114; q=1 and (m+n+p)q=114    -   c) 3.0% of a monomer of formula (IIb) in which        -   R represents the vinyl group        -   A is absent        -   B represents the methyl radical            of intrinsic viscosity equal to 20.0 ml/g according to the            above-mentioned intrinsic viscosity method, to obtain, from            a calcium carbonate with a median diameter of 15 μm, and            under the same operating conditions and using the same            equipment as in test No. 1, an aqueous suspension of ground            calcium carbonate having a dry matter concentration equal to            75% by weight and having a grain size such that 63% by            weight of the particles have a diameter of less than 2 μm            measured on the Sedigraph™ 5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=74.5%

Viscosity (T₀)=145 mPa·sAVAG viscosity (T_(7 days))=285 mPa·sAPAG viscosity (T_(7 days))=112 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand of the calcium carbonate is determined using the samemethod as in test No. 1. This gives a PDDPC cationic polymer demandequal to 2500 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

Test No. 19

This test illustrates the invention and implements 1.10% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 18 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 93% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=74.0%

Viscosity (T₀)=249 mPa·sAVAG viscosity (T_(7 days))=1260 mPa·sAPAG viscosity (T_(7 days))=279 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand of the calcium carbonate is determined using the samemethod as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 4040 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

Test No. 20

This test illustrates the invention and implements 2.10% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 18 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to 75%by weight and having a grain size such that 83% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=74.3%

Viscosity (T₀)=808 mPa·sAVAG viscosity (T_(7 days))=3000 mPa·sAPAG viscosity (T_(7 days))=802 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand of the calcium carbonate is determined using the samemethod as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 7710 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

Test No. 21

This test illustrates the invention and implements 0.27% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to65.1% by weight and having a grain size such that 60% by weight of theparticles have a diameter of less than 2 μm measured on the Sedigraph™,corresponding to a median diameter equal to 1.50 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=65.1%

Viscosity (T₀)=183 mPa·sAVAG viscosity (T_(7 days))=354 mPa·sAPAG viscosity (T_(7 days))=205 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand is determined using the same method as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 410 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=600 seconds for h=6 cm and t_(disp)=immediate.

These results show that much less foam is created than in the test ofthe prior art.

Test No. 22

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to76.0% by weight and having a grain size such that 74% by weight of theparticles have a diameter of less than 2 μm, and 39% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™,corresponding to a median diameter equal to 1.25 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=76.0%

Viscosity (T₀)=295 mPa·sAVAG viscosity (T_(7 days))=505 mPa·sAPAG viscosity (T_(7 days))=195 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand of the calcium carbonate is determined using the samemethod as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 550 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

In this test, a measurement was made of the foam using the sameoperating procedure as in test No. 5 and the result was:

t=600 seconds for h=6 cm and t_(disp)=immediate.

These results show that much less foam is created than in the test ofthe prior art.

EXAMPLE 2

This example illustrates the link between filler retention in fillingand cationic polymer demand.

Test No. 23

This test illustrates the prior art and implements 0.27% by dry weight,with respect to the dry weight of calcium carbonate, of a sodium andmagnesium polyacrylate of intrinsic viscosity equal to 7.8 ml/gaccording to the above-mentioned intrinsic viscosity method, to obtain,from a calcium carbonate with a median diameter of 15 μm, an aqueoussuspension of ground calcium carbonate having a dry matter concentrationequal to 65.5% by weight and having a grain size such that 61% by weightof the particles have a diameter of less than 2 μm and 30% by weight ofthe particles have a diameter of less than 1 μm measured on theSedigraph™ 5100 corresponding to a median diameter equal to 1.63 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=65.5%

Viscosity (T₀)=115 mPa·sAVAG viscosity (T_(7 days))=620 mPa·sAPAG viscosity (T_(7 days)) 155 mPa·s

Filler retention in the filling is determined using the method describedbelow and simulating prevalent conditions for a sheet of paper of agrammage equal to 80 g/m² and charged to 20% by weight.

The filler retention value then corresponds to the equation

${{Filler}\mspace{14mu} {retention}} = {\frac{{{{Turb}.\mspace{11mu} {of}}\mspace{14mu} {incoming}\mspace{14mu} {body}} - {{{Turb}.\mspace{14mu} {wire}}\mspace{14mu} {water}}}{{{Turb}.\mspace{14mu} {of}}\mspace{14mu} {incoming}\mspace{14mu} {body}} \times 100}$

where Turb.=turbidityTurb. of incoming body=Turb. of fibre-filler mixture−Turb. of fibre

To do this, it is therefore necessary to measure, on the one hand, theturbidity of the fibre-filler mixture and, on the other hand, theturbidity of the fibre alone and the turbidity of the water of thefabric.

This latter is measured directly by reading the value of the turbidityindicated by the Nephelometer 155 from Defensor AG (Switzerland) in NTU(Nephelo Turbidity Unit) units.

On the other hand, to determine the turbidity of the fibre-fillermixture, a fibre-filler mixture is made from a masterbatch formed bydiluting 4 parts of fibres consisting of 80% birch and 20% pine in 10litres of water. 18.2 dry grams of the fibre masterbatch and 9.8 gramsof the dry filler to be tested are added to a device known as adistributor (Rapid-Köthen) and topped up with 5 litres of water. After15 minutes of stirring and the addition of the quantities indicated intable 1 below, of a retaining agent of the polyacrylamide type marketedunder the name Praestol™ PK 422, by Stockhausen, Krefeld, Germany, amixture that simulates the prevalent conditions for a sheet of paper ofgrammage equal to 80 g/m² and charged to 20% by weight is obtained.

The mixture thus formed is dried in a vacuum of 0.2 bar for over 2seconds.

The values, at 700 rpm, of filler retentions in the filling, obtained bymeans of the above equation and as a function of the cationic retainingagent rate of the polyacrylamide type marketed under the name Praestol™PK 422, by Stockhausen (Germany) are shown in table 1 below.

TABLE 1 0.01% PK 0.02% PK 0.03% PK 0.04% PK 0.05% PK 422 422 422 422 4225% filler 14% filler 26% filler 29% filler 31% filler retentionretention retention retention retention

Test No. 24

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 15 μm, and under the same operating conditions andusing the same equipment as in test No. 1, an aqueous suspension ofground calcium carbonate having a dry matter concentration equal to75.8% by weight and having a grain size such that 62% by weight of theparticles have a diameter of less than 2 μm, and 32% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™,corresponding to a median diameter equal to 1.57 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=75.8%

Viscosity (T₀)=175 mPa·sAVAG viscosity (T_(7 days))=505 mPa·sAPAG viscosity (T_(7 days))=195 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand of the calcium carbonate is determined using the samemethod as in test No. 1.

The filler retention in the filling is determined using the sameprocedure and the same equipment as those used in the previous test.

The values, at 700 rpm, of filler retentions in the filling, obtained bymeans of the above equation and as a function of the rate of cationicretaining agent of the polyacrylamide type marketed under the namePraestol™ PK 422, by Stockhausen (Germany) are shown in table 2 below.

TABLE 2 0.01% PK 0.02% PK 0.03% PK 0.04% PK 0.05% PK 422 422 422 422 42215% filler 26% filler 38% filler 47% filler 54% filler retentionretention retention retention retention

Tables 1 and 2 point to a better filler retention for the test accordingto the invention.

EXAMPLE 3

This example illustrates, by means of a comparison with identical grainsize, how to reduce the cationic polymer demand in the filling byimplementing an aqueous suspension of calcium carbonate containing thecopolymer used, according to the invention, as a grinding aid agent, forvarious grinding processes.

Test No. 25

This test illustrates the invention and implements, as dispersant beforethe grinding stage, 0.1% by dry weight, with respect to the dry weightof calcium carbonate, of a sodium and magnesium polyacrylate of anintrinsic viscosity equal to 7.8 ml/g according to the above-mentionedintrinsic viscosity method, and as a grinding aid agent during thegrinding stage, 0.27% by dry weight, with respect to the dry weight ofcalcium carbonate, of the copolymer implemented in test No. 6 to obtain,from a calcium carbonate with a median diameter of 15 μm, with the sameequipment as in test No. 1, a suspension of ground calcium carbonatehaving a dry matter concentration equal to 65.0% by weight and having agrain size such that 59% by weight of the particles have a diameter ofless than 2 μm, and 34% by weight of the particles have a diameter ofless than 1 μm measured on the Sedigraph 5100 corresponding to a mediandiameter equal to 1.58 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=65.0%

Viscosity (T₀)=163 mPa·sAVAG viscosity (T_(7 days))=319 mPa·sAPAG viscosity (T_(7 days))=185 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand of the calcium carbonate is determined using the samemethod as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 1620 μVal/kg.

It can thus be seen that the cationic polymer demand is lower than thatof the prior art for equivalent grain size.

Test No. 26

This test illustrates the invention and implements, as a grinding aidagent, 1.8% by dry weight with respect to the dry weight of calciumcarbonate, of the copolymer implemented in test No. 6 to obtain, via atwo-stage grinding process, a 74.7% by dry matter weight suspension ofcalcium carbonate with grain size such that 98% by weight of theparticles have a diameter of less than 2 μm and 78% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100.

This two-stage grinding process consists in grinding, during the firststage, a suspension of calcium carbonate of initial average diameterequal to 5 μm measured using the Sedigraph™ 5100 particle size analyzerin an aqueous suspension of calcium carbonate to a grain size such that62% by weight of the particles have a diameter of less than 2 μm and 37%by weight of the particles have a diameter of less than 1 μm measuredusing the Sedigraph™ 5100, then in grinding this suspension until thedesired end grain size is obtained.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=74.7%

Viscosity (T₀)=750 mPa·sAPAG viscosity (T_(7 days))=680 mPa·s

Once these Brookfield™ viscosity measurements have been made, thespecific surface area and the cationic demand of the calcium carbonateare determined using the same method as in test No. 1.

This gives a BET specific surface area of the pigment obtained,determined according to standard ISO 9277, equal to 7.5 m²/g and a PDDPCcationic polymer demand equal to 4140 μVal/kg.

EXAMPLE 4

This example illustrates, by means of a comparison with identical grainsize, how to reduce the cationic polymer demand in the filling byimplementing an aqueous suspension of various mineral matter containingthe copolymer used, according to the invention, as a grinding aid agent.

Test No. 27

This test illustrates the invention and implements 0.40% by dry weight,with respect to the dry weight of aluminium trihydroxide, of thecopolymer implemented in test No. 6 to obtain, from an aluminiumtrihydroxide with a median diameter equal to 50 μm, and under the sameoperating conditions and using the same equipment as in test No. 1, anaqueous suspension of ground aluminium trihydroxide having a dry matterconcentration equal to 51.4% by weight and having a grain size such that48.8% by weight of the particles have a diameter of less than 2 μm, and29.4% by weight of the particles have a diameter of less than 1 μmmeasured on the Sedigraph™ 5100, corresponding to a median diameterequal to 2.00 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=48.8%

Viscosity (T₀)=62 mPa·sAVAG viscosity (T_(7 days))=115 mPa·sAPAG viscosity (T_(7 days))=95 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand is determined using the same method as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 590 μVal/kg.

It can therefore be seen that the cationic polymer demand is low.

Test No. 28

This test illustrates the invention and implements 0.40% by weight, withrespect to the dry weight of talc, of the copolymer implemented in testNo. 6 to obtain, from a talc of median diameter equal to 15.7 μm or witha grain size such that 14% by weight of the particles have a diameter ofless than 5 μm, 4% by weight of the particles have a diameter of lessthan 1 μm measured on the Sedigraph™ 5100 and under the same operatingconditions and with the same equipment as in test No. 1, an aqueoussuspension of ground talc having a dry matter concentration equal to28.3% by weight and having a grain size such that 41% by weight of theparticles have a diameter of less than 5 μm, and 12% by weight of theparticles have a diameter of less than 1 μm measured on the Sedigraph™5100 corresponding to a median diameter equal to 6.3 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=28.3%

Viscosity (T₀)=219 mPa·sAVAG viscosity (T_(7 days))=415 mPa·sAPAG viscosity (T_(7 days))=134 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand is determined using the same method as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 520 μVal/kg.

It can therefore be seen that the cationic polymer demand is low.

Test No. 29

This test illustrates the invention and implements 0.40% by weight, withrespect to the dry weight of kaolin, of the copolymer implemented intest No. 6 to obtain, from a kaolin of median diameter equal to 0.33 μmor with a grain size such that 92% by weight of the particles have adiameter of less than 0.5 μm, 4% by weight of the particles have adiameter of less than 0.2 μm measured on the Sedigraph™ 5100 and underthe same operating conditions and with the same equipment as in test No.1, an aqueous suspension of ground kaolin having a dry matterconcentration equal to 15% by weight and having a grain size such that95% by weight of the particles have a diameter of less than 0.5 μm, and7% by weight of the particles have a diameter of less than 0.2 μmmeasured on the Sedigraph™ 5100 corresponding to a median diameter equalto 0.30 μm.

The dry matter concentration (S.C.: Solid Content) and Brookfield™viscosity results obtained with the same measuring method as test No. 1are as follows:

S.C.=15.0%

Viscosity (T₀)=244 mPa·sAVAG viscosity (T_(7 days))=212 mPa·sAPAG viscosity (T_(7 days))=199 mPa·s

Once these Brookfield™ viscosity measurements have been made, thecationic demand is determined using the same method as in test No. 1.

This gives a PDDPC cationic polymer demand equal to 420 μVal/kg.

It can therefore be seen that the cationic polymer demand is low.

EXAMPLE 5

This example illustrates, via measurement of the gloss and by comparisonat identical grain size, the stability of the coating colour obtained byimplementing an aqueous suspension of calcium carbonate according to theinvention.

To do this in each of the tests of the example, it is necessary toprepare a coating colour with 68% concentration of dry matter,consisting of:

-   -   80 parts by dry weight of the calcium carbonate aqueous        suspension to be tested,    -   5 parts by dry weight of a coarser calcium carbonate slurry,    -   15 parts of delaminated kaolin    -   9.5 parts of binder    -   0.32 parts of carboxymethyl cellulose,    -   0.6 parts of polyvinyl alcohol    -   0.15 parts of optical brightener, and    -   0.4 parts of calcium stearate

Once the coating colour is prepared in this manner, its Brookfield™viscosity is measured using a model DV-II+ Brookfield™ viscometer fittedwith the corresponding spindle.

The coating colour prepared is then applied to a wood based paper 53 μmthick and with a grammage equal to 82, using a Combiblades pilot coaterfrom Jagenberg GmbH fitted with a 0.457 mm thick blade.

A long dwell time application head is used with a blade angle of 45°.The coating speed is 1000 m/s and the average coating deposited is 11g/m² on each surface of the paper.

The relative humidity obtained for each paper is of the order of 4.2% to4.6% weight for weight.

The paper thus coated is then calendered using a supercalender with 9contact zones between the two rollers, marketed by Kleinewefers.

The iron calendering diameter is 180 mm and 270 mm with respect to thecotton.

The measurement of the 75° TAPPI gloss (standard TAPPI T480 os-78)according to Lehmann of the coated and calendered paper, which consistsin passing the coated and calendered paper sheet in the laboratory glossmeter (LGDL-05/2 from Lehmann Messtechnik AG, Switzerland) determinesthe supercalendering.

Once this gloss measurement is made, the paper samples are cut into DINA3 format and are conditioned in an air conditioned room as per standardDIN EN 20187 to determine the 75° DIN gloss values according to standardDIN 54 502, and the 45° DIN gloss values according to standard DIN 54502.

Test No. 30

This test illustrates the prior art and implements a suspension ofcalcium carbonate of the prior art.

To do this, in order to prepare the coating colour to be tested thecomposition of which is as described above, 22.5 kg of an aqueoussuspension, of 78.2% dry matter concentration, of coarser calciumcarbonate marketed by Omya under the name Hydrocarb™ 60, and 356.5 kg ofan aqueous suspension, with 78.5% dry matter concentration, of finercalcium carbonate marketed by Omya under the name Setacarb™ are mixed ina receptacle containing 20 kg of water and 0.125 kg of a sodiumpolyacrylate with dry matter concentration equal to 42% and intrinsicviscosity equal to 6.2 ml/g as per the above-mentioned intrinsicviscosity method.

Once the calcium carbonates have been mixed, 52.5 kg of a delaminatedkaolin marketed by Kaolin International B.V. under the name Amazon™ 88are added while stirring at average speed.

Stirring is continued at average speed for 15 minutes and, followingvisual verification of whether or not agglomerates are present, stirringis continued until the few agglomerates disappear, or is stopped ifthere are no agglomerates.

7.5 kg of a 15% aqueous solution of carboxymethyl cellulose previouslydissolved for at least 20 minutes at least 90° C. and marketed byNoviant under the name CMC Finnfix™ 10 are then added.

8.4 kg of a 25% aqueous solution of polyvinyl alcohol previouslydissolved for at least 20 minutes at least 90° C. and marketed byClariant under the name Mowiol™ 4-98 are then added.

28 kg of an 50% by dry weight aqueous dispersion of styrene-butadienemarketed by Dow Europe under the name Dow Latex DL 940 and 38.5 kg of a50% by dry weight aqueous dispersion of an acrylic ester copolymermarketed by BASF under the name Acronal™ 360 D are then added as binder.

Finally, 1.9 kg of optical brightener in the form of an aqueousderivative of 4,4-diaminostilbene-2,2-disulfonic acid marketed by Bayerunder the name Blancophor™ P and 2.8 kg of a 50% concentration by dryweight aqueous dispersion of a calcium stearate sold by Henkel-Nopco ASunder the name Nopcote™ C-104 are added.

Once these additions are made, stirring is maintained for another 15minutes.

The pH of the coating colour is then checked and brought to a value ofapproximately 9 by means of a 10% soda solution.

The dry matter content of the coating colour is also checked and broughtto a value of approximately 68.5% by adding water if necessary.

The Brookfield™ viscosity of the coating colour obtained as measured at32° C. using the Brookfield™ DV-II+ model viscometer fitted with thecorresponding spindle is equal to 6100 mPa·s at 20 min⁻¹ and 1800 mPa·sat 100 min⁻¹.

The various gloss measurements are made in accordance with theabove-mentioned method and are shown in table 3 following the next test.

Test No. 31

This test illustrates the invention and implements the suspension ofcalcium carbonate of test No. 26 according to the invention.

To do this, in order to prepare the coating colour to be tested thecomposition of which is as described above, 22.5 kg of an aqueoussuspension, of 78.2% dry matter concentration, of coarser calciumcarbonate marketed by Omya under the name Hydrocarb™ 60, and 375 kg ofthe aqueous suspension of calcium carbonate of test No. 26 according tothe invention, with 74.7% dry matter concentration are mixed in areceptacle containing 20 kg of water and 0.125 kg of a sodiumpolyacrylate with dry matter concentration equal to 42% and intrinsicviscosity equal to 6.2 ml/g as per the above-mentioned intrinsicviscosity method.

Once the calcium carbonates have been mixed, 52.5 kg of a delaminatedkaolin marketed by Kaolin International B.V. under the name Amazon™ 88are added while stirring at average speed.

Stirring is continued at average speed for 15 minutes and, followingvisual verification of whether or not agglomerates are present, stirringis continued until the few agglomerates disappear, or is stopped ifthere are no agglomerates.

7.5 kg of a 15% aqueous solution of carboxymethyl cellulose previouslydissolved for at least 20 minutes at least 90° C. and marketed byNoviant under the name CMC Finnfix™ 10 are then added.

8.4 kg of a 25% aqueous solution of polyvinyl alcohol previouslydissolved for at least 20 minutes at least 90° C. and marketed byClariant under the name Mowiol™ 4-98 are then added.

28 kg of an 50% by dry weight aqueous dispersion of styrene-butadienemarketed by Dow Europe under the name Dow Latex DL 940 and 38.5 kg of a50% by dry weight aqueous dispersion of an acrylic ester copolymermarketed by BASF under the name Acronal™ S 360 D are then added asbinder.

Finally, 1.9 kg of optical brightener in the form of an aqueousderivative of 4,4-diaminostilbene-2,2-disulfonic acid marketed by Bayerunder the name Blancophor™ P and 2.8 kg of a 50% concentration by dryweight aqueous dispersion of a calcium stearate sold by Henkel-Nopco ASunder the name Nopcote™ C-104 are added.

Once these additions are made, stirring is maintained for another 15minutes.

The pH of the coating colour is then checked and brought to a value ofapproximately 9 by means of a 10% soda solution.

The dry matter content of the coating colour is also checked and broughtto a value of approximately 68.5% by adding water if necessary.

The Brookfield™ viscosity of the coating colour obtained as measured at32° C. using the Brookfield™ DV-II+model viscometer fitted with thecorresponding spindle is equal to 3600 mPa·s at 20 min⁻¹ and 1200 mPa·sat 100 min⁻¹.

The various gloss measurements are made in accordance with theabove-mentioned method and are shown in table 3 below.

TABLE 3 Prior art Invention Test Test Standard Unit No. 32 No. 33 coatedpaper 1301 ISO 536 g/m² 102 105 (75° TAPPI) OS gloss TAPPI % 75 80 (75°TAPPI) SS gloss TAPPI % 77 82 (75° DIN) OS gloss DIN 54 502 % 46 50 (75°DIN) SS gloss DIN 54 502 % 48 54 (45° DIN) OS gloss DIN 54 502 % 17 23(45° DIN) SS gloss DIN 54 502 % 19 28 (PPS) 1.0 soft OS ISO 8791-4 μm0.610 0.579 roughness (PPS) 1.0 soft SS ISO 8791-4 μm 0.608 0.530roughness OS = Upper surface (Oberseite) SS = Fabric side or rear side(Siebseite)

The table shows that paper coated using coating colours containingaqueous suspensions of calcium carbonate according to the invention havea higher gloss irrespective of the viewing angle and a lower roughnessthan paper coated with standard coating colours of the prior art.

EXAMPLE 6

This example illustrates the use of the aqueous suspension according tothe invention in a drying process.

Test No. 32

This test illustrates the prior art and implements 0.35% by dry weight,with respect to the dry weight of calcium carbonate, of a sodium andmagnesium polyacrylate of intrinsic viscosity equal to 7.8 ml/gaccording to the above-mentioned intrinsic viscosity method, to obtain,from a calcium carbonate with a median diameter of 15 μm, an aqueoussuspension of ground calcium carbonate having a dry matter concentrationequal to 36.9% by weight and having a grain size such that 73% by weightof the particles have a diameter of less than 2 μm and 46% by weight ofthe particles have a diameter of less than 1 μm measured on theSedigraph™ 5100 corresponding to a median diameter equal to 1.17 μm.

The aqueous suspension obtained is then dried using a dryer such as theMedia Slurry Drier MSD 100 from Nara Machinery CO., LTD (Japan). Thedrying capacity obtained is then equal to 1220 g/h of dry product.

Test No. 33

This test illustrates the invention and implements 0.45% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 15 μm, an aqueous suspension of ground calciumcarbonate having a dry matter concentration equal to 36.9% by weight andhaving a grain size such that 74% by weight of the particles have adiameter of less than 2 μm, and 44% by weight of the particles have adiameter of less than 1 μm measured on the Sedigraph™, corresponding toa median diameter equal to 1.18 μm.

The aqueous suspension obtained is then dried using a dryer such as theMedia Slurry Drier MSD 100 from Nara Machinery CO., LTD (Japan). Thedrying capacity obtained is then equal to 1542 g/h of dry product, thusbringing about an increase of 21% in the drying capacity.

Test No. 34

This test illustrates the prior art and implements 0.45% by dry weight,with respect to the dry weight of calcium carbonate, of a sodium andmagnesium polyacrylate of intrinsic viscosity equal to 7.8 ml/gaccording to the above-mentioned intrinsic viscosity method, to obtain,from a calcium carbonate with a median diameter of 0.72 μm, an aqueoussuspension of ground calcium carbonate having a dry matter concentrationequal to 33.3% by weight and having a grain size such that 98% by weightof the particles have a diameter of less than 2 μm and 84% by weight ofthe particles have a diameter of less than 1 μm measured on theSedigraph™ 5100 corresponding to a median diameter equal to 0.60 μm.

The aqueous suspension obtained is then dried using a dryer such as theMedia Slurry Drier MSD 100 from Nara Machinery CO., LTD (Japan). Thedrying capacity obtained is then equal to 1,018 g/h of dry product.

Test No. 35

This test illustrates the invention and implements 0.45% by dry weight,with respect to the dry weight of calcium carbonate, of the copolymerimplemented in test No. 6 to obtain, from a calcium carbonate with amedian diameter of 0.72 μm, an aqueous suspension of ground calciumcarbonate having a dry matter concentration equal to 33.3% by weight andhaving a grain size such that 98% by weight of the particles have adiameter of less than 2 μm, and 81% by weight of the particles have adiameter of less than 1 μm measured on the Sedigraph™, corresponding toa median diameter equal to 0.67 μm.

The aqueous suspension obtained is then dried using a dryer such as theMedia Slurry Drier MSD 100 from Nara Machinery CO., LTD (Japan). Thedrying capacity obtained is then equal to 1,093 g/h of dry product, thusbringing about an increase of 7% in the drying capacity.

EXAMPLE 7

This example illustrates the use of the dried slurry of calciumcarbonate according to the invention in the field of plastics and moreparticularly in a PVC application, by comparing the dispersion, in arigid PVC formulation, of a dried slurry of natural calcium carbonateaccording to the invention and according to the prior art by comparisonof the rheological behaviour obtained.

To do this, for each of the tests of the example, the mixturecorresponding to the following formulation, in parts, is prepared, withthe exception of test No. 36 which does not contain calcium carbonate:

PVC EVAPOLSH 6521 marketed by EVC (Germany) 100 tribasic lead sulphate1.5 dibasic lead stearate 1.3 calcium stearate 0.6 Wax E 0.05 Calciumcarbonate to be tested 30.0

This mixture is prepared in a Papenmeier mixer at 100° C. for 10minutes. The mixtures are then gelated on a rotating cylinder at 20 rpmat 170° C. in a mixing chamber of the MP Göttfert extrusion meterVersion 2.3.0.

The rheological behaviour is then evaluated by measuring the gelationtime of the mixture.

Test No. 36—Control Without Filler

This test is a control test which relates to the above-mentionedformulation but without calcium carbonate.

The gelation time obtained is equal to 738 seconds.

Test No. 37

This test illustrates the prior art and implements the dried product oftest No. 32.

The gelation time obtained is equal to 720 seconds for a formulationwith 30 parts of filler, i.e. an increase of 2.5% with respect to thefiller-free control.

Test No. 38

This test illustrates the invention and implements the dried product oftest No. 33.

The gelation time obtained is equal to 562 seconds for a formulationwith 30 parts of filler, i.e. an increase of 23.8% with respect to thefiller-free control.

These results show that a dry product of the invention can be favourablyused in the field of plastics, and more particularly in rigid PVCformulations.

1-33. (canceled)
 34. An aqueous suspension of refined mineral mattercomprising refined mineral matter and a grinding aid agent, wherein thegrinding agent comprises a copolymer of: a) at least one ethylenicallyunsaturated anionic monomer having (i) a monocarboxyl function selectedfrom ethylenically unsaturated monomers having a monocarboxyl function,or (ii) a dicarboxyl function selected from ethylenically unsaturatedmonomers having a dicarboxyl function or (iii) a sulfonic functionselected from ethylenically unsaturated monomers having a sulfonicfunction, or (iv) a phosphoric function selected from ethylenicallyunsaturated monomers having a phosphoric function, or (v) a phosphonicfunction selected from ethylenically unsaturated monomers having aphosphonic function or mixtures thereof, b) at least one non-ionicethylenically unsaturated monomer of formula (I):

where m and p represent a number of alkylene oxide units less than orequal to 150, n represents a number of ethylene oxide units less than orequal to 150, q represents an integer equal to at least 1 and such that5≦(m+n+p)q≦150, R₁ represents hydrogen or the methyl or ethyl radical,R₂ represents hydrogen or the methyl or ethyl radical, R represents aradical containing a polymerizable unsaturated function, R′ representshydrogen or a hydrocarbon radical having from 1 to 40 carbon atoms, or amixture of several monomers of formula (I), c) at least oneorganofluorinated or organosilylated monomer selected from among themolecules of formulae (IIa) or (IIb) or (IIc) or mixtures thereof: withformula (IIa)

where m1, p1, m2 and p2 represent a number of alkylene oxide units lessthan or equal to 150, n1 and n2 represent a number of ethylene oxideunits less than or equal to 150, q1 and q2 represent an integer equal toat least 1 and such that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150, rrepresents a number such that 1≦r≦200, R₃ represents a radicalcontaining a polymerizable unsaturated function, R₄, R₅, R₁₀ and R₁₁represent hydrogen or the methyl or ethyl radical, R₆, R₇, R₈ and R₉represent straight or branched alkyl, aryl, alkylaryl or arylalkylgroups having from 1 to 20 carbon atoms, or a mixture thereof, R₁₂represents a hydrocarbon radical having from 1 to 40 carbon atoms, A andB are groups which may be present, in which case they represent ahydrocarbon radical having from 1 to 4 carbon atoms, with formula (IIb)R-A-Si(OB)₃ where R represents a radical containing a polymerizableunsaturated function, A is a group which may be present, in which caseit represents a hydrocarbon radical having from 1 to 4 carbon atoms, Brepresents a hydrocarbon radical having from 1 to 4 carbon atoms, withformula (IIc)

where m3, p3, m4 and p4 represent a number of alkylene oxide units lessthan or equal to 150, n3 and n4 represent a number of ethylene oxideunits less than or equal to 150, q3 and q4 represent an integer equal toat least 1 and such that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150, r′represents a number such that 1≦r′≦200, R₁₃ represents a radicalcontaining a polymerizable unsaturated function, R₁₄, R₁₅, R₂₀ and R₂₁represent hydrogen or the methyl or ethyl radical, R₁₆, R₁₇, R₁₈ and R₁₉represent straight or branched alkyl, aryl, alkylaryl or arylalkylgroups having from 1 to 20 carbon atoms, or a mixture thereof, D and Eare groups which may be present, in which case they represent ahydrocarbon radical having from 1 to 4 carbon atoms, d) optionally atleast one monomer of the acrylamide or methacrylamide type or theirderivatives or mixtures thereof, or at least one non water-solublemonomer, or at least one cationic monomer or quaternary ammonium, e)optionally at least one crosslinking monomer selected from the groupconsisting of ethylene glycol dimethacrylate,trimethylolpropanetriacrylate, allyl acrylate, the allyl maleates,methylene-bis-acrylamide, methylene-bis-methacrylamide,tetrallyloxyethane, triallylcyanurates, and allyl ethers prepared frompolyols, the total of the components a), b), c), d) and e) being equalto 100%, and having an intrinsic viscosity less than or equal to 100ml/g determined in accordance with the method known as the intrinsicviscosity method.
 35. Paper, paint or plastic comprising a pigmentprepared from the aqueous suspension of mineral matter according toclaim
 34. 36. Paper comprising a pigment prepared from the aqueoussuspension of mineral matter according to claim 34, wherein the pigmentis included in the coating or surface treatment of the paper.
 37. Paper,board, or analogous sheets comprising a pigment prepared from theaqueous suspension of mineral matter according to claim 34, wherein thepigment is included as a filler in the paper, board or analogous sheets.38. Paper or board sheets comprising a pigment prepared from the aqueoussuspension of mineral matter according to claim
 34. 39. Plasticscomprising a pigment prepared from the aqueous suspension of mineralmatter according to claim
 34. 40. A grinding aid agent for mineralmatter in aqueous suspension, wherein the grinding agent comprises acopolymer of: a) at least one ethylenically unsaturated anionic monomerhaving (i) a monocarboxyl function selected from ethylenicallyunsaturated monomers having a monocarboxyl function, or (ii) adicarboxyl function selected from ethylenically unsaturated monomershaving a dicarboxyl function or (iii) a sulfonic function selected fromethylenically unsaturated monomers having a sulfonic function, or (iv) aphosphoric function selected from ethylenically unsaturated monomershaving a phosphoric function, or (v) a phosphonic function selected fromethylenically unsaturated monomers having a phosphonic function, ormixtures thereof, f) at least one non-ionic ethylenically unsaturatedmonomer of formula (I):

where m and p represent a number of alkylene oxide units less than orequal to 150, n represents a number of ethylene oxide units less than orequal to 150, q represents an integer equal to at least 1 and such that5≦(m+n+p)q≦150, R₁ represents hydrogen or the methyl or ethyl radical,R₂ represents hydrogen or the methyl or ethyl radical, R represents aradical containing a polymerizable unsaturated function, R′ representshydrogen or a hydrocarbon radical having from 1 to 40 carbon atoms, or amixture of several monomers of formula (I), g) at least oneorganofluorinated or organosilylated monomer selected from among themolecules of formulae (IIa) or (IIb) or (IIc) or mixtures thereof: withformula (IIa)

where m1, p1, m2 and p2 represent a number of alkylene oxide units lessthan or equal to 150, n1 and n2 represent a number of ethylene oxideunits less than or equal to 150, q1 and q2 represent an integer equal toat least 1 and such that 0≦(m1+n1+p1)q1≦150 and 0≦(m2+n2+p2)q2≦150, rrepresents a number such that 1≦r≦200, R₃ represents a radicalcontaining a polymerizable unsaturated function, R₄, R₅, R₁₀ and R₁₁represent hydrogen or the methyl or ethyl radical, R₆, R₇, R₈ and R₉represent straight or branched alkyl, aryl, alkylaryl or arylalkylgroups having from 1 to 20 carbon atoms, or a mixture thereof, R₁₂represents a hydrocarbon radical having from 1 to 40 carbon atoms, A andB are groups which may be present, in which case they represent ahydrocarbon radical having from 1 to 4 carbon atoms, with formula (IIb)R-A-Si(OB)₃ where R represents a radical containing a polymerizableunsaturated function, A is a group which may be present, in which caseit represents a hydrocarbon radical having from 1 to 4 carbon atoms, Brepresents a hydrocarbon radical having from 1 to 4 carbon atoms, withformula (IIc)

where m3, p3, m4 and p4 represent a number of alkylene oxide units lessthan or equal to 150, n3 and n4 represent a number of ethylene oxideunits less than or equal to 150, q3 and q4 represent an integer equal toat least 1 and such that 0≦(m3+n3+p3)q3≦150 and 0≦(m4+n4+p4)q4≦150, r′represents a number such that 1≦r′≦200, R₁₃ represents a radicalcontaining a polymerizable unsaturated function, R₁₄, R₁₅, R₂₀ and R₂₁represent hydrogen or the methyl or ethyl radical, R₁₆, R₁₇, R₁₈ and R₁₉represent straight or branched alkyl, aryl, alkylaryl or arylalkylgroups having from 1 to 20 carbon atoms, or a mixture thereof, D and Eare groups which may be present, in which case they represent ahydrocarbon radical having from 1 to 4 carbon atoms, h) optionally atleast one monomer of the acrylamide or methacrylamide type or theirderivatives or mixtures thereof, or at least one non water-solublemonomer, or at least one cationic monomer or quaternary ammonium, i)optionally at least one crosslinking monomer selected from the groupconsisting of ethylene glycol dimethacrylate,trimethylolpropanetriacrylate, allyl acrylate, the allyl maleates,methylene-bis-acrylamide, methylene-bis-methacrylamide,tetrallyloxyethane, triallylcyanurates, and allyl ethers prepared frompolyols, the total of the components a), b), c), d) and e) being equalto 100%, and having an intrinsic viscosity less than or equal to 100ml/g determined in accordance with the method known as the intrinsicviscosity method.
 41. A process for grinding mineral matter in aqueoussuspension consisting of refining an aqueous suspension of said mineralmaterials into very fine particles characterized in that use is made, asa grinding aid agent before and/or during the grinding stage, of 0.05%to 10% by dry weight, with respect to the dry weight of mineral matter,of the copolymer according to claim 40 and in that use may be made of atleast one other dispersant or grinding aid agent before and/or duringthe grinding stage.